AMAX STEREO
IC CHIPSET
DW SUFFIX
PLASTIC PACKAGE
CASE 751D
(SO–20L)
20
1
Order this document from Analog Marketing
DW SUFFIX
PLASTIC PACKAGE
CASE 751F
(SO–28L)
28
1
20
1
28
1
MC13027
MC13122
P SUFFIX
PLASTIC PACKAGE
CASE 710
P SUFFIX
PLASTIC PACKAGE
CASE 738
1
MOTOROLA ANALOG IC DEVICE DATA
The MC13027 and MC13122 have been specifically designed for AM
radio which can meet the EIA/NAB AMAX requirements. They are
essentially the same as the MC13022A and MC13025 with the addition of
noise blanking circuitry. The noise blanker consists of a wide band amplifier
with an RF switch for blanking ahead the IF amplifier and a stereo audio
blanker with adjustable delay and blanking times.
• Operating Voltage Range of 6.0 V to 10 V
• RF Blanker with Built–In Wide Band AGC Amplifier
• Audio Noise Blanker with Audio Track and Hold
• Mixer Third Order Intercept of 8.0 dBm (115 dBµV)
• Wide Band AGC Detector for RF Amplifier
• Local Oscillator VCO Divide–by–4 for Better Phase Noise
• Buffered Local Oscillator Output at the Fundamental Frequency
• Fast Stereo Decoder Lock
• Soft Stereo Blend
• Signal Quality Detector to Control Variable Q–Notch Filters for Adaptive
Audio Bandwidth and Whistle Reduction
• Signal Quality Detector for AM Stereo
• Very Low Distortion Envelope and Synchronous Detectors
• Variable Bandwidth IF
ORDERING INFORMATION
Device
Operating
Temperature Range
Package
MC13027DW
SO–20L
MC13027P
–
°
°
Plastic DIP
MC13122DW
T
A
= –
40 ° to +85°C
SO–28L
MC13122P Plastic DIP
Fast
AGC
Control
Audio
Blanking
Functional Block Diagram
Oscillator
Buffer
Voltage
Controlled
Oscillator
Wide Band
AGC
AM
Detector
Automatic
Gain Controlled
RF Amplifier
Pulse
Detector
÷
4 Mixer
IF Amplifier
IF Amplifier
AGC
Shunt
Switch
Pulse Length
Timer
Pulse Delay
Timer
Signal Quality
Detector
Pilot
Detector
Decoder
Track & Hold
Post Detector
Filter
450 kHz IF
Signal Level
450 kHz Blend cos
θ
Fast Lock
Control
Stereo Indicator Lamp
Stop–Sense
RF AGC Meter Drive
Right Audio
Left Audio
Y es/NoI
RF
Blanking
AGC
Output
To Synthesizer
Osc
Tank
AGC
Input
RF
Input
RF Input
L
R
Q
Fast/
Slow
MC13027 MC13122
This device contains 428 active transistors. This device contains 670 active transistors.
Pulse Length
Timer
This document contains information on a product under development. Motorola reserves the
right to change or discontinue this product without notice.
Motorola, Inc. 1996 Issue 1
MC13027 MC13122
2
MOTOROLA ANALOG IC DEVICE DATA
MC13027
MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Input Voltage V
CC
12 Vdc
Ambient Operating Temperature T
A
–40 to +85 °C
Storage Temperature Range T
stg
–60 to +150 °C
Operating Junction Temperature T
J
150 °C
NOTE: ESD data available upon request.
MC13027
ELECTRICAL CHARACTERISTICS (T
A
= 25°C, 8.0 VCC Test Circuit as shown in Figure 1.)
Characteristic
Min Typ Max Unit
Supply Voltage Range (Pin 8) – 6.0 to 10 – V
Wideband (WB) AGC Threshold – 1.0 – mVrms
IF Output DC Current – 1.0 – mAdc
Mixer DC Current Output – 0.83 – mAdc
Local Oscillator Output – 600 – mVpp
Wideband AGC Pull–Down Current (Pin 20) – 1.0 – mAdc
Power Supply Current – 16 – mAdc
Mixer 3rd Order Intercept Point (Pin 6) – 8.0 – dBm
Mixer Conversion Gain – 2.9 – mS
IF Amplifier Input Impedance (Pin 14) – 2.2 – kΩ
IF Amplifier Transconductance – 2.8 – mS
IF Amplifier Load Resistance (Pin 16) – 5.7 – kΩ
IF Amplifier Collector Current (Pin 16) – 990 – µA
MC13027 MC13122
3
MOTOROLA ANALOG IC DEVICE DATA
Figure 1. MC13027 Test Circuit
34
RF In
1
2
3
4
5
6
7
8
V
CC
Gnd
Mixer In
Mixer 4.0 V
Tuning V
VCLO
VCLO 4.0 V
C87
0.1
R2
82
R1
100 k
RL2
51
RM2
16.7
R299
51
RM1
16.7
Pulse In
RF In
Pulse On
RF
Mixer In
Blanker In
WB AGC
RL1
51
R10
56 k
C5
22
µ
F
C14
47
µ
F
R200
560 k
V
CC
V
CC
On
R4
47
R11
47
Q1
MMBFJ309L
RM5
16.7
CM1
0.01
C11
0.1
C293
10
µ
F
C6
0.1
R201
120
C37
0.01
100
LO Out
Tuning Voltage 4.0 V Reg
C9
47
µ
F
C16
10
µ
F
C26
1.0
µ
F
C10
0.01
R20
47 k
C90
0.1
R3b
10 k
R18
2.35 k
R1b
10 k
R16
3.3 k
RT1
39 k
Q2
(Note 1)
Q3
(Note 1)
R19
500 k
R17
500 k
R15
500 k
C103
0.1
R12
1.8 k
Q1b
(Note 1)
R5b
390 k
R21
510
C16 120
L2 1.0 mH
Murata
SFG450E
20
19
18
17
16
15
14
13
12
11
1
2
3
4
5
6
7
8
9
10
WB AGC
Out
Audio
Blank Time
Audio
Blank Pulse
Audio Blank
Delay Time
IF Out
RF Blank
Time
IF In
Gnd2
RF Blank
Mixer Out
WB AGC
In
Blanker
AGC
Feedback
4.0 V Reg
RF Gnd
Mixer In
Blanker RF In
4.0 Filter
V
CC
VCO
LO Out
WB AGC Out
Audio Blank
IF Out
RF Blank
R2b
10 k
12
5
V
CC
AGC Feedback
MC13027
RF Module
Q4
MMBT3904L
V
CC
V
CC
+
+
+
+
+
+
NOTE: 1.General purpose NPN transistor 2N3904 or equivalent.
MC13027 MC13122
4
MOTOROLA ANALOG IC DEVICE DATA
MC13122
MAXIMUM RATINGS
Rating Symbol Value Unit
Power Supply Input Voltage V
CC
12 Vdc
Stereo (Pilot) Indicator Lamp Current (Pin 21) – 30 mAdc
Operating Ambient Temperature T
A
–40 to +85 °C
Storage Temperature Range T
stg
–65 to +150 °C
Operating Junction Temperature T
J(max)
150 °C
Power Dissipation Derated above 25°C P
D
1.25 Ω
p
D
10 mW/C
NOTE: ESD data available upon request.
MC13122
ELECTRICAL CHARACTERISTICS
(VCC = 8.0 V , TA = 25°C, Test Circuit of Figure 2.)
Characteristic
Min Typ Max Unit
Power Supply Operating Range 6.0 8.0 10 V
Supply Current Drain (Pin 25) 10 20 25 mA
Minimum Input Signal Level, Unmodulated, for AGC Start – 5.0 – mV
Audio Output Level, 50% Modulation, L Only or R Only 290 400 530 mV rms
Audio Output Level, 50% Mono 140 200 265 mV rms
Output THD, 50% Modulation (Monaural Stereo) – 0.3 0.8 %
p, ( )
– 0.5 1.6
Channel Separation, L Only or R Only, 50% Modulation 22 35 – dB
IF Input Voltage Range – 1.0–1000 – mV
IF Input Resistance Range – 10 to 50 –
kΩ
IF Amplifier Transconductance – 9.6 – mS
IF Detector Circuit Impedance – 8.3 – kΩ
Input AGC Threshold – 5.0 – mV
Stop–Sense Output Range – 2.2 to 4.0 – V
Audio Output Impedance at 1.0 kHz (Pins 7 and 14) – 300 – Ω
Stereo Indicator Lamp Leakage – – 1.0 µA
Stereo Indicator Saturation Voltage @ 3.0 mA – – 200 mVdc
Oscillator Capture Range – ±3.0 – kHz
MC13027 MC13122
5
MOTOROLA ANALOG IC DEVICE DATA
Figure 2. MC13122 Test Circuit
MC13122
IC2
U2
THB122
1
Ch2 Out
2
3
4
5
6
Ch2 Cont
Ch2 In
Ch1 In
Ch1 Cont
Ch1 Out
23
I Det
24
25
26
27
28
L–R Det
Q Det
V
CC
Loop Filt
Blend
17
Gnd
18
19
20
21
22
Pilot Ind
Osc Out
Osc In
Pilot Det I
Pilot I
16
Pilot Q
15
Audio Blank
E Det
Det In
3.0 V Reg
AGC
IF In
SS
L Out
L Filt In
L Filt Ctr
L Mat Out
R Mat Out
R Filt Ctr
R Filt In
R Out
6
5
4
3
2
1
12
11
10
9
8
7
13
14
R10
13 k
C3 47
µ
F
C4 10 µF
450 kHz IF In
SS Out Left
Audio Out
Right
Audio Out
C6
1.0
µ
F
C1
1000
.01
100 k
R6
10 k
R5
C28
1000
C27
1000
10001000
33 k
R11
C16
0.47
µ
F
C17
10 µF
C31
1.0
µ
F
1000 C30
3.9 k
R12
C18
22
µ
F
1.0 k
R20
X1
3.6 MHz
AF Blank
Blend Disable
8.0 V
Envelope Det Out
I Detector Out
Q Detector Out
2.2 k
R26
C23 22
µ
F
C24 47
µ
F
C22
220
µ
F
Stereo
D1
CA
MPS6515
Q3
C
B
E
51 C29
L1
1.0 mH
C2
120
MC13027 MC13122
6
MOTOROLA ANALOG IC DEVICE DATA
AMAX STEREO CHIPSET
What is AMAX?
In 1993, a joint proposal by the EIA (Electronic Industries
Association) and the NAB (National Association of
Broadcasters) was issued. It included a unified standard for
pre–emphasis and distortion for broadcasters as well as a set
of criteria for the certification of receivers. The purpose of this
proposal was to restore quality and uniformity to the AM band
and to make it possible for the consumer to receive high
quality signals using the AM band. The FCC has been
supportive of this initiative and has required all new
broadcast licensees to meet AMAX standards. The NAB and
EIA have continued to encourage receiver manufacturers by
offering the AMAX certification logo to be displayed on all
qualifying radios. This logo is shown below.
or
The Receiver Criteria
An AMAX receiver must have wide bandwidth: 7.5kHz for
home and auto, 6.5 kHz for portables. It must have some
form of bandwidth control, either manual or automatic,
including at least two bandwidth provisions, such as “narrow”
and “wide”. It must meet NRSC receiver standards for
distortion and deemphasis. It must have provisions for an
external antenna. It must be capable of tuning the expanded
AM band (up to 1700 kHz). And finally, home and auto
receivers must have effective noise blanking. All of these
requirements, except the noise blanking, have been met by
Motorola’s previous AM radio products, such as MC13025
Front End and the MC13022A C–QUAM stereo decoder. It is
the Noise Blanker requirement which is met by the two
devices on this data sheet, the MC13027 and MC13122.
Noise blanking, especially in AM auto radios, has become
extremely important. The combination of higher energy
ignitions, using multiple spark coils, along with increased use
of plastic in the auto body, have increased the noise energy
at the radio. Also, the consumer has learned to expect higher
quality audio due to advances in many other media. For the
AM band to sustain interest to the consumer, a truly effective
noise blanker is required.
The block diagram below shows the Motorola AMAX
stereo chipset. It offers a two–pronged approach to noise
blanking which is believed to be the most effective yet offered
in the consumer market. The initial blanking takes place in
the output of the mixer, using a shunt circuit triggered by a
carefully defined wideband receiver. For most noises, some
residual audible disturbance is almost always still present
after this process. The disturbance becomes stretched and
delayed as it passes through the rest of the selectivity in the
receiver. The stretching and delay are predictable, so the
MC13027 can provide a noise blanking pulse with the correct
delay and stretch to the output stages of the MC13122
decoder. The MC13122 has a Track and Hold circuit which
receives the blanking signal from the Front End and uses it to
gently hold the audio wherever it is as the pulse arrives, and
hold that value until the noise has passed. The combined
effect is dramatic. A wide range of types of noise is
successfully suppressed and the resulting audio seems
almost clean until the noise is so intense that the blanking
approaches full–time.
The amount of extra circuitry to accomplish noise blanking
is relatively small. The external components for this added
capability are shown in Figure 3. In the MC13027 Front end,
the noise receiver/detector requires two capacitors. The
presettings for blanking timing and blanking delay require
three external fixed resistors. Finally the decoder requires
two track and hold capacitors to store the “audio” voltage
during the track and hold function.
Figure 3. AMAX Stereo Receiver with Noise Blanker
MC13027 MC13122
Audio Blank
450 kHz
Filter
RF Attenuate
Left
Right
RF In
Pin
Diode
Reset
AGC
RF
Amplifier
Mixer
IF
Amplifier
AGC’d IF
Amplifier
AM
Stereo
Decoder
Track
and
Hold
Variable
Notch Filter
Wideband
AGC
4.0 V
Regulator
Divide
by 4
VCO
RF
Attenuator
Switch
RF Blank
Timer
AGC’d RF
AmplifierAMDetector
Audio
Reject
Filter
Pulse
Detector
Delay
Timer
Audio Blank
Timer
Audio
Blank
Switch
MC13027 MC13122
7
MOTOROLA ANALOG IC DEVICE DATA
Figure 4. MC13027 Internal Block Diagram
20 19 18 17 16 15 14 13 12 11
12345678910
WB AGC Amp
Mixer
IF Amp
NB Amp
V
CC
÷
4
RF Time
MV
AF Del
MV
AF Time
MV
X1
Reg
X1
WB AGCInBlanker
AGC
Feedback 4.0 V Reg RF Gnd Mixer In
Blanker RF In
4.0 Filter V
CC
VCO LO Out
WB AGC
Out
Audio
Blank Time
Audio
Blank Pulse
Audio Blank
Delay Time
IF Out
RF Blank
Time
IF In Gnd2 RF Blank Mixer Out
MC13027 FUNCTIONAL DESCRIPTION
The MC13027 contains the mixer, wide band AGC
system, local oscillator, IF pre–amplifier and noise blanker for
an AM radio receiver. It is designed to be used with the
MC13122 to produce a complete AM stereo receiver. The
VCO runs at 4 (Fin+FIF) and is divided internally by 4 for the
mixer input and local oscillator buffered output. Dividing the
VCO reduces the phase noise for AM stereo applications.
The noise blanker input is connected in parallel with the
mixer input at Pin 6. The noise blanker circuitry contains a
high gain amplifier with its own AGC so it remains linear
throughout the mixer’s linear range. It can detect noise
pulses as low as 120 µV and generates three pulses when
the noise threshold is exceeded. The width and timing of the
blanking pulses is set by the resistors connected to Pins 15,
17 and 19. The resistor on Pin 15 sets the length of the RF
blanking pulse and determines the time the transistor on
Pin 12 is “on”. The audio blanking pulse delay is set by the
resistor on Pin 17 and the width by the resistor on Pin 19.
This is necessary because the IF filtering delays and
stretches the noise as it arrives at the detector. The transistor
on Pin 18 goes “on” to cause noise blanking in the track and
hold circuit in the MC13122 (Pin 15).
Wideband AGC is used in auto receivers to prevent
overload – it drives the base of a cascode transistor RF
amplifier and also a pin diode at the antenna (See Figures 6
and 7).
A low gain IF amplifier between Pins 14 and 16 is used as
a buffer amplifier between the mixer output filter and IF filter.
The input resistance of the IF amplifier is designed to match
a ceramic IF filter. The gain of the IF amplifier is determined
by the impedance of the load on Pin 16.
MC13027 MC13122
8
MOTOROLA ANALOG IC DEVICE DATA
Figure 5. MC13122 Internal Block Diagram
28 27 26 25 24 23 22
1234567
21 20 19 18
891011
17 16 15
12 13 14
I L–R Q
V
CC
VGA
±
0.9
VGA
±
0.9
LR
LevelFast AGC
1.0 V
3.0 V
AGC
Matrix
C–QUAM
Comparator
Blend
Disable
450 <90
°
450 <0
°
Signal
Quality
Detector
÷
32
÷
137/144
÷
4
Count
Control
Clamp
25.6 Hz 24.4 Hz
Fast Lock
VCO
Loop
Driver
Pilot
Level
Det
÷
8
Pilot I
Det
Pilot Q
Det
cos
θ
330
Loop
Filt
Blend Gnd Pilot Ind Osc Out Osc In Pilot Det I Pilot I Pilot Q
Audio
Blank
L–R
L+R
IF Amp
V
CC
Q DetL–R DetI Det
IF In SS L Out L Filt In L Filt Ctr L Mat
Out
R Mat
Out
R Filt
Ctr
R Filt In R OutAGC3.0 V
Reg
Det InE Det
MC13122 FUNCTIONAL DESCRIPTION
The MC13122 is designed to accept a 450 kHz C–QUAM
input signal from approximately 1.0 mV to 1.0 V and produce
L and R audio output signals. It has additional features: stop
signal, variable bandwidth IF and audio response, stereo
indicator driver and track and hold noise blanking.
The IF amplifier on Pin 5 has its own AGC system. It
operates by varying the input resistance on Pin 5. With weak
signals below approximate 5.0 mV, the input resistance is
very high and the amplifier is at maximum gain. For this AGC
to be effective, it is necessary to feed the IF input signal from
a relatively high impedance. The input resistance variation
also reduces the Q of the coil (T1 in the application) so the
receiver bandwidth is narrow for weak signals and wide for
strong signals. The value of the input resistor (R5) is selected
for the desired loading of the IF coil. The impedance of the IF
coil on Pin 2 determines the IF gain. Pin 2 is also the input to
the C–QUAM decoder.
The IF signal drives the envelope (E), in–phase (I),
quadrature (Q) and (L–R) detectors. The E detector is a
quasi–synchronous true envelope detector. The others are
true synchronous detectors. The E detector output provides
the L+R portion of the C–QUAM signal directly to the matrix.
The AGC signal of the IF amplifier drives the signal strength
output at Pin 6. An external resistor on Pin 6 (sets the gain of
the AGC). The Pin 6 voltage is used to control the Q of the
audio notch filter, causing the audio bandwidth and depth of
the 10 kHz notch to change with signal strength. It is also
used as one of the inputs to the signal quality detector which
generates the stop–sense and blend signal on Pins 6 and 23
respectively and tells the signal quality detector that the RF
input is below the AGC threshold.
VCO
The 3.6 MHz ceramic resonator on Pins 19 and 20 is part
of a phase locked loop which locks to the 450 kHz IF signal.
The 3.6 MHz is divided by 8 to produce in–phase and
quadrature signals for the I, Q and L–R detectors. It is also
divided by 32, and 137/144 to provide signals for the pilot I
and Q detectors. The pilot detector is a unique circuit which
does not need filtering to detect the 25 Hz pilot.
Blend Circuit
The purpose of the blend circuit is to provide an AM stereo
radio with the capability of very fast lock times, protection
against stereo falsing when there is no pilot present and
control of the L–R signal so as to provide as much stereo
information as possible, while still sounding good in the
presence of noise or interference. The circuit also provides
an optional stop–sense usable by a radio with seek and/or
scan. The stop–sense signal provides a “stop” signal only
when the radio is locked on station, signal strength is above
minimum level, and the level of interference is less than a
predetermined amount. The last feature prevents stopping
on frequencies where there is is a multiplicity of strong
co–channel stations. It is common for AM radios without this
capability to stop on many frequencies with unlistenable
stations, especially at night.
The blend circuit controls the PLL fast lock, pilot detector,
IF amplifier AGC rate, decoder L–R gain, cosθ compensation
and stop–sense as a function of the voltage on a signal
external blend capacitor. Timing is determined by the rate of
change of voltage on the blend cap. Timing is changed by
varying charge and discharge current and pulled down by a
current source, switch, and optionally an external switch. The
current sources and switches are controlled by various
measures of signal quality, signal strength, and presence or
absence of pilot tone.
MC13027 MC13122
9
MOTOROLA ANALOG IC DEVICE DATA
Detectors
In AM stereo operation, the Q detector delivers pilot signal
via an external low–pass filter to the pilot detector input (Pin
18). The E and I detectors drive the C–QUAM comparator.
The L–R signal and the output of the envelope detector are
combined in the matrix to produce the L and R signals. The
C–QUAM system modifies the in–phase and quadrature
components of the transmitted signal by the cosine of the
phase angle of the resultant carrier, for proper stereo
decoding. An uncompensated L–R would be distorted,
primarily by second harmonics. Where there is noise or
interference in the L–R, it has been subjectively determined
that reducing the cosθ compensation at the expense of
increased distortion sounds better than full decoding. The
blend line operates over a small voltage range to eliminate
cosine compensation.
Signal Quality Detector – Blend Voltage Control
The signal quality detector output is dependent on signal
strength, over–modulation, and whether or not the blend pin
has been pulled low prior to searching. Over–modulation
usually occurs when a radio is tuned one channel away from
a desired strong signal, so this prevents stopping one
channel away from a strong signal.
In a radio tuned to a strong, interference free C–QUAM
station, the blend voltage will be approximately 3.6 V. In the
presence of noise or interference, when the modulation
envelope is at a minimum, it is possible for the I detector to
produce a negative, or below zero carrier signal. The Signal
Quality Detector produces an output each time the negative
I exceeds 4%. The output of the detector sets a latch. The
output of the latch turns on current source which pulls down
the voltage of the blend cap at a predetermined rate. The
latch is then reset by a low frequency signal from the pilot
detector logic. This produces about a 200 mV change each
time 4% negative I is detected. Tables 1 and 2 describe the
blend behavior under various conditions.
When the blend voltage reaches 2.2 V a blend control
circuit starts to reduce the amplitude of the L–R signal fed to
the decoder matrix. By 1.5 V the L–R has been reduced by
about 40 dB. At lower voltages it is entirely off and the
decoder output is monaural. This reduction of L–R signal, or
blend as it is commonly called when done in FM stereo
radios, reduces undesirable interference effects as a function
of the amount of interference present.
Stop–Sense
Stop–sense is enabled when the blend voltage is
externally pulled below 0.45 V. An input from the AGC
indicating minimum signal, or detection of 10% negative I will
cause the stop–sense pin to be pulled low. With signals
greater than the AGC corner and less than 10% interference
the stop–sense will be a minimum of 1.0 V below the 3.0 V
line. Very rapid scanning is possible because the radio can
scan to the next frequency as soon as the stop–sense goes
low. The maximum wait time, set by the radio, is only reached
on good stations.
The decoder will not lock on an adjacent channel because
it is out of the lock range of the PLL. The beat note produced
in the I detector by the out of lock condition will trigger the
10% negative I detector.
Sequence For Seek Scan
• Change Station – Pull–Down Blend
• Wait Approximately 50 ms for Synthesizer and Decoder
PLL to Lock
• Observe Pin 6 Voltage
• If it is Above 2.0 V and Stays Above 2.0 V for
Approximately 800 ms, Stay on the Station
• No IF Count Now Needed
• No AGC Level Detector Needed
Table 1. Normal Sequence When Changing Stations
External Pull–Down of
Blend Capacitor to Under
0.47 V
– Increased Current Supplied to
Loop Driver for Fast Lock
– Fast AGC Activated
– Extra Current Pull–Up Activated
on Blend Capacitor
– Pilot Detector Disabled
– Loop Locks
– Stop–Sense Activated
Blend Released – Blend Capacitor Pulled Up to
0.7 V – Stops
– Fast Lock Current Removed
– Fast AGC Turned Off
– Pilot Detector Enabled
Pilot Detected – Stereo Indicator Pin Pulled Low
– Blend Voltage Pulled Positive
Rapidly
Blend Voltage Reaches
1.4 V
– Audio Starts Into Stereo
– 10% Negative I Detector
Enabled
Blend Voltage Reaches
2.2 V
– Stereo Separator Reaches 20
to 25 dB
– Rapid Current Pull–Up Turned
Off
– 4% Negative I Detector Enabled
Blend Voltage Reaches
3.0 V
– cosθ Enabled – Full C–QUAM
Decoding
– Blend Voltage Continues to Rise
to 3.6 V and Stops
Table 2. Operation In Adverse Conditions
4% Negative I Detected – Blend Pulls Down
Approximately 200 mV for Each
Event – Acts Like One–Shot
– Stops at 2.2 V – cosθ Has Been
Defeated, Almost Full Stereo
Remains
10% Negative I Detected – Blend Pulls Down 200 mV for
Each Event
– Stops at 1.4 V – Stereo Has
Blended to Mono
– Resets Fast Pull–Up if Blend
Has Not Been Above 2.2 V
50% Negative I Detected
(Out of Lock)
– Blend Pulls Down Fast During
Event
– Stops at 0.47 V
– Resets Fast Pull–Up
– Pilot Indicator Turned Off
Minimum Signal Level
Detected
– Resets Fast Pull–Up
– Pulls Down to 0.7 V
MC13027 MC13122
10
MOTOROLA ANALOG IC DEVICE DATA
MC13027 PIN FUNCTION DESCRIPTION
Pin Name
Internal Equivalent Circuit Description
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
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WB AGC In
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V
CC
1
3.3 V
WB AGC In
R2
15 k
20 k
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Wideband AGC Input
The input impedance to the WB AGC detector is
15 k and is internally biased so it must be coupled
through a capacitor. The threshold can be
increased by adding a resistor in series with the
input. The WB AGC begins at about 1.0 mV . In car
radios, this input should be connected to the
collector of the RF amplifier cascode stage through
a resistor and capacitor. A 68 pF to ground will
prevent undesired high frequency signals from
activating the WB AGC and make the sensitivity
more uniform across the band.
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Blanker AGC
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2
NB AGC
D1
D2
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Blanker AGC
The capacitor to ground is the bypass for the noise
blanker AGC circuit. The noise blanker can be
disabled by grounding this pin. 10 µF is used in the
application, but it can be changed to match the
time constant of the main IF AGC in the MC13122,
Pin 4.
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3
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Feedback
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3
NB Feedback
11 k
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Blanker Feedback
This pin is the dc feedback to the input stage of the
wide band amplifier.
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4
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4.0 V Reg
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4
7
4.0 V Reg
4.0 V Filter
Buffer
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4.0 V Regulator
The 4.0 V regulator supplies low impedance bias to
many of the circuits in the IC. It should be
bypassed to a ground near Pin 5.
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7
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4.0 V Filt
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V
CC
4.7 k
Reg
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4.0 V Filter
The external capacitor works with internal 4.7 k to
filter noise from the bandgap regulator.
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5
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Gnd
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5
RF Gnd
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RF Ground
This pin is the ground for the RF section, blanker
RF, filters and all radio circuits except the IF. In the
PCB layout, the ground pin should be used as the
internal return ground in the RF circuits.
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6
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BlkRF/Mix
In
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6
11
Mixer Out
Mixer/
Blanker In
LO +
V
CC
50
Ω
50
Ω
50
Ω
50
Ω
V
CC
4.0 V
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Mixer Input/Blanker RF Input
The blanker RF input must be biased from the
4.0 V on Pin 4. The mixer input is to two bases of
the upper mixer transistors. A low impedance dc
path to the 4.0 V on Pin 4 is required. Normally,
this would be a coil secondary connected between
Pins 6 and 4.
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11
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Mixer Out
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750
LO–
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Mixer Output
A single ended output of a double balanced mixer.
A load resistor to supply is chosen to match the
ceramic filter, typically 1.5 k to 1.8 k. Output
current is 830 µA.
MC13027 MC13122
11
MOTOROLA ANALOG IC DEVICE DATA
MC13027 PIN FUNCTION DESCRIPTION (continued)
Description
Pin Internal Equivalent CircuitName
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8
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V
CC
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8
V
CC
V
CC
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Supply Voltage
The normal operating voltage range is 6.0 to 10 V .
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9
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VCLO
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9
V
CC
VCLO
4.0 V
1.5 k
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Voltage Control Local Oscillator
The oscillator is a cross coupled negative
resistance type and this pin must be connected
through a low dc resistance to Pin 4, the 4.0 V
regulator. Normally, this would be the secondary of
the oscillator coil.
The impedance of the secondary winding should
be around 2.8 kΩ to guarantee that the oscillator
will run. It operates at 4 times the LO frequency:
f
osc
= 4(Fin+FIF).
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10
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LO Out
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10
V
CC
390
LO Out
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Local Oscillator Output
This is an emitter follower for LO output to drive a
synthesizer. It is a square wave output, the internal
series resistance and allows a small bypass to
reduce high frequency harmonics.
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12
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RF Blank
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12
100 k
RF Blk
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RF Blanker
An unbiased NPN acts as a SHUNT impedance
when turned on. The 100 k resistor provides a dc
path for the capacitor.
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13
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Gnd2
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13
Gnd
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IF Ground
Pin 13 is the ground for the IF section and the
timing and switching circuits in the blanker.
In the application circuit this should be common to
the MC13122 ground.
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14
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IF In
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16
V
CC
4.0 V
220
Ω
IF Out
2.2 k
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IF Input
A degenerated differential amplifier internally
biased to 4.0 V . The IF input impedance is
approximately 1.8 k to match a ceramic filter. The
IF amplifier is used as a buffer between the
ceramic filter and the detector coil and has a fixed
gain determined by the impedance of the output
coil.
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16
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IF Out
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14
3.4 k 3.4 k
IF In
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IF Output
An open collector provides high–impedance drive
to the MC13122; the IF gain is set by the ac
impedance on this pin.
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15
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RF Time
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15
4.0 V
10 k
RF Blk Time
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RF Blank Time
A resistor to ground sets the RF blanking time. The
time is set to the minimum required to attenuate
the pulse received. This is normally longest at the
low end of the band. The value is best approved by
ear. A fixed value can be chosen for production.
(50 µs is typical.)
MC13027 MC13122
12
MOTOROLA ANALOG IC DEVICE DATA
MC13027 PIN FUNCTION DESCRIPTION
(continued)
Description
Pin Internal Equivalent CircuitName
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Á
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Á
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Á
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17
ÁÁÁ
Á
ÁÁÁ
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ÁÁÁ
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ÁÁÁ
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ÁÁÁ
Á
Delay Time
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БББББББББББББ
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17
4.0 k
10 k
Audio
Delay Time
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Audio Blank Delay Time
A resistor to ground sets the delay time from the
beginning of the RF blanking pulse to the
beginning of the audio blanking pulse. This
normally is about 50 µs for a wide AMAX filter. The
ear is the most sensitive measure of the correct
delay; start low, say 20 µs, and vary delay until
noise is heard, and then reduce somewhat.
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18
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Á
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Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Audio Blank
Cntl
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18
V
CC
Audio Blank
4.7 k
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Audio Blank Pulse
When the blanker is operating, a positive pulse
from this pin is fed to Pin 15 of the MC13122 to
blank the audio signal.
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19
ÁÁÁ
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ÁÁÁ
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Á
ÁÁÁ
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ÁÁÁ
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Audio Time
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19
V
CC
10 k
Audio
Blk Time
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Audio Blank Time
A resistor to ground sets the width of the blanking
pulse on Pin 18. This is usually selected by
applying a pulse to the antenna of the receiver and
adjusting a variable resistor. The blanking signal
should be just long enough to suppress the audio
pulse. Again the ear is the most sensitive tool.
Start long, approximately 250 µs and reduce until
noise is audible then increase.
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20
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
WB AGC Out
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БББББББББББББ
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БББББББББББББ
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БББББББББББББ
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БББББББББББББ
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БББББББББББББ
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20
V
CC
440
Ω
330
Ω
WB AGC Out
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БББББББББББ
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Wideband AGC Output
A push–pull current output. The resistor to voltage
source (normally VCC) determines the gain. Used
to bias a cascode transistor in series with the input
FET and can also be used to drive a PNP
transistor which drives a pin diode attenuator (refer
to Application Circuit Figure 6.)
MC13027 MC13122
13
MOTOROLA ANALOG IC DEVICE DATA
MC13122 PIN FUNCTION DESCRIPTION
Pin Name
Internal Equivalent Circuit Description
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Á
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Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
1
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
E Detector
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БББББББББББББ
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БББББББББББББ
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БББББББББББББ
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БББББББББББББ
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1
V
CC
Envelope Det
6.2 k
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Á
Envelope Detector
This is the output of the envelope detector and is
used for one input to the comparator that
generates cosθ signal and the L+R input to the
matrix. It is a quasi–synchronous full wave detector
with very low distortion (<1% at 100% modulation).
The output impedance is 6.2 k, and it is bypassed
to VCC with 1.0 nF to eliminate 900 kHz
components. The bypass capacitor must be the
same as the one on Pin 27 and 28 for lowest
stereo distortion and best separation.
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Á
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Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
2
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Detector In
БББББББББББББ
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2
Det In
V
CC
120
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IF Out/Decoder Input
The IF coil is connected from Pin 2 to Pin 3, the
3.0 V regulator. The IF amplifier output is a current
source. The gain is determined by the impedance
between Pins 2 and 3. Bandwidth and gain is set
by the resistance across the coil.
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3
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3.0 V Reg
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3
3.0 V Reg
3.0 V
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Á
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Á
3.0 V Regulator
This bandgap regulator supplies bias to many of
the circuits in the IC.
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4
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AGC Byp
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4
IF AGC
2.3 V
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IF AGC Bypass
The AGC has a fast and slow time constant. The
fast AGC is 18X the slow one and is active when
the 450 kHz loop is not locked. This allows for fast
scanning in car radios. This capacitor should be
selected for distortion for low frequencies at 80%
modulation.
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5
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IF In
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БББББББББББББ
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Á
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Á
БББББББББББББ
Á
5
IF In
10 k
AGC Current
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Á
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Á
IF Input
The IF AGC varies the current through attenuator
diodes. The diodes vary the input impedance
shunting the IF signal. The varying impedance also
varies the Q and therefore the bandwidth. The IF
AGC is accomplished by turning on the diodes and
lowering the IF input impedance.
MC13027 MC13122
14
MOTOROLA ANALOG IC DEVICE DATA
MC13122 PIN FUNCTION DESCRIPTION
(continued)
Description
Pin Internal Equivalent CircuitName
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Á
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Á
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Á
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6
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
SS
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
6
Stop–Sense
1.0 k
20 k
V
CC
3.0 V
Signal
Strength
Stop–Sense
Pull–Down
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Á
Signal Strength/Stop–Sense
The signal strength is a push–pull circuit. The
voltage is 2.2 V at minimum signal and 3.5 to 5.0 V
at strong signal. This dc voltage is also used to
control the audio output notch filters. If the Blend
pin is low the stop–sense is activated and this pin
can go low. This can be used to control the
seek–scan in the radio.
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7
14
ÁÁÁ
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ÁÁÁ
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Á
Left Out
Right Out
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БББББББББББББ
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БББББББББББББ
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V
CC
7
L Out
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Á
Filtered Left and Filtered Right Output
This can drive a de–emphasis filter to bring audio
contour to AMAX specifications. Since the output is
an emitter follower, the output impedance is low,
and a series R should be used with the
de–emphasis network as shown on the application
circuit.
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8
13
ÁÁÁ
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Á
L Filt In
R Filt In
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8
L Filter In
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Input to Notch Filter
DC bias is supplied through the external filter
components.
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9
12
ÁÁÁ
Á
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L Filt Ctr
R Filt Ctr
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Á
9
L Filter Ctr
Op Amp
20 k 20 k
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Left Filter and Right Filter Center
Drives the center leg of a twin–T filter, varying the
Q. At strong signal, positive feedback narrows the
notch, and there is little HF roll–off. At weak signal,
negative feedback produces a broad notch and HF
roll–off.
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10
11
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Á
L Matrix Out
R Matrix Out
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10
L Matix Out
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Á
Track and Hold Output
This is a unity gain operational amplifier output.
The current is turned off by the blanking pulse. The
capacitor holds output voltage constant until
unblanked. Internal feedback causes the output
impedance to be low.
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15
ÁÁÁ
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AF Blank In
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БББББББББББББ
15
4.7 k
Audio Blank
4.7 k
R
L
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Á
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Audio Blank Control
The current to the output drivers is turned off.
MC13027 MC13122
15
MOTOROLA ANALOG IC DEVICE DATA
MC13122 PIN FUNCTION DESCRIPTION (continued)
Description
Pin Internal Equivalent CircuitName
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Á
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Á
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Á
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Á
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Á
16
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Pilot Q
БББББББББББББ
Á
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Á
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БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
16
Pilot Q
3.0 V
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Á
Pilot Q
This is the output of a quadrature detector of a
narrowband phase locked loop system.
It is used to control the pilot detector circuitry. The
pilot Q is clamped to the 3.0 V reference when the
blend voltage is pulled low. This results in faster
pilot detection when a stereo station is tuned in. If
the blend is not pulled low, the pilot Q will drift up
approximately 0.5 V when there is no pilot, and it
will take longer to detect the pilot. The capacitor to
ground is the loop filter. It sets the pilot loop
bandwidth: if it is too large, the loop bandwidth
maybe too small, and the pilot may not be
re–acquired if it is lost unless the blend pin is
externally pulled low again.
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17
ÁÁÁ
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Á
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Á
ÁÁÁ
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Á
Pilot I
БББББББББББББ
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Á
17
Pilot I
3.0 V
47 k
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Á
Pilot I
When the loop is locked to a 25 Hz AM stereo pilot,
this is the output of a an in–phase synchronous
detector. The capacitor filters the output, which is
used to drive the pilot indicator driver on Pin 21.
The time constant for the pilot indicator output is
determined by this capacitor and the internal 47 k
resistor. If the capacitor is too small, it can lead to
pilot falsing due to noise. If the capacitor is too
large, the acquisition time increases. The cap is
charged to 3.0 V when the blend voltage is low to
shorten lock time.
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18
ÁÁÁ
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Á
Pilot Det In
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18
Pilot Det In
VCC3.0 V
47 k
39 k
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Á
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Á
Pilot Detector Input
The pilot detector will detect a pilot tone between
24.4 and 25.6 Hz. The pilot signal is fed from Q
detector through a low pass filter on Pin 26. The
audio signals from the Q detector must be filtered
out, so a low–pass filter is used. The capacitor in
series with Pin 18 blocks dc and prevents large low
frequency transients from knocking the decoder
out of stereo mode.
ÁÁ
Á
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Á
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Á
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Á
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19
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Osc In
БББББББББББББ
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Á
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БББББББББББББ
Á
19
Osc Input
VCC3.0 V
10 k
22 k
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Á
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Á
Oscillator Input
The input impedance is 10 k, but the
recommended circuit adds 3.9 k in parallel with this
to control the capture range of the VCO to be
around ±3.0 kHz. using the recommended ceramic
resonator.
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Á
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Á
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Á
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20
ÁÁÁ
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Á
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ÁÁÁ
Á
Osc Out
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Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
20
Osc Feedback
V
CC
100
БББББББББББ
Á
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Á
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Á
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Á
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Á
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Á
Oscillator Output
The internal phase shift of the VCO is 90 degrees,
and the output impedance is low. It is designed to
drive a resonant circuit with a 90 degree phase
shift at the center frequency.
MC13027 MC13122
16
MOTOROLA ANALOG IC DEVICE DATA
MC13122 PIN FUNCTION DESCRIPTION
(continued)
Description
Pin Internal Equivalent CircuitName
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
21
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Pilot
Indicator
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
10
21
27 k
Pilot Indicator
БББББББББББ
Á
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Á
БББББББББББ
Á
БББББББББББ
Á
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Á
БББББББББББ
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БББББББББББ
Á
Pilot Indicator
The maximum current is internally limited to protect
the IC, but it should be operated with a current
limiting resistor.
ÁÁ
Á
ÁÁ
Á
22
ÁÁÁ
Á
ÁÁÁ
Á
Gnd
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Á
БББББББББББББ
Á
22
Gnd
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Á
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Á
Ground
Use good practices to keep oscillator returns and
RF bypasses to good copper near this point
ÁÁ
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Á
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Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
23
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Blend Cont
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
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Á
БББББББББББББ
Á
23
Blend
330
3.0 V
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Á
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Á
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Á
БББББББББББ
Á
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БББББББББББ
Á
БББББББББББ
Á
Blend Control
There are pull–up and pull–down currents provided
to this pin. The external capacitor controls the rate
of change of this voltage and 22 µF is
recommended. This is an important voltage
affecting many functions in the IC.
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
24
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Loop Filt
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
24
Loop Filter
3.0 V
330
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
Loop Filter
The phase detector is a current source, so only a
single RC loop filter is needed for a second order
loop. The internal 330 Ω resistor together with a
47 µF gives the correct corner frequency and
damping for the proper operation on the decoder
loop. The cap should be low leakage to avoid static
phase error.
ÁÁ
Á
ÁÁ
Á
25
ÁÁÁ
Á
ÁÁÁ
Á
V
CC
БББББББББББББ
Á
БББББББББББББ
Á
25
V
CC
V
CC
БББББББББББ
Á
БББББББББББ
Á
V
CC
The operating voltage is normally 8.0 to 10 V in car
radios. The MC13122 will work from 6.0 to 10 V .
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
26
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
Q Detector
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
26
Q Det Out
11 k
3.0 V
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
Q Detector Output
This is a synchronous detector in quadrature with
the 450 kHz IF signal. The output impedance is
11 k. This signal is normally used for input to the
pilot detector and internally for the fast lock.
MC13027 MC13122
17
MOTOROLA ANALOG IC DEVICE DATA
MC13122 PIN FUNCTION DESCRIPTION (continued)
Description
Pin Internal Equivalent CircuitName
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
27
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
L–R Detector
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
27
L–R Det
V
CC
6.2 k
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
L–R Detector
This is similar to the Q detector output but its level
is controlled by the blend circuit. When the blend is
active, the L–R output is reduced in level by
reducing the dc current until mono operation is
reached. It operates in the same way as the blend
circuit in FM stereo decoders. The bypass
capacitor should be 1.0 nF as on Pin 1 for optimum
channel separation.
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
ÁÁ
Á
28
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
ÁÁÁ
Á
I Detector
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
БББББББББББББ
Á
28
I Det
V
CC
6.2 k
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
БББББББББББ
Á
I Detector
This is a synchronous detector in phase with the
450 kHz IF signal. It is used internally to generate
the cosθ signal and as an input to the signal quality
detector. The bypass capacitor should be the same
as the one on Pin 1 for best separation and lowest
stereo distortion.
MC13027 MC13122
18
MOTOROLA ANALOG IC DEVICE DATA
CAR RADIO APPLICATION
Figure 6 shows a car radio circuit using a TOKO pre–tuned
RF module. The RF module includes a 4 diode tracking circuit
to eliminate mistracking between the oscillator and RF circuits
over the 530 to 1700 kHz AM band. This is important for stereo
performance because mistracking will cause mono distortion
and will significantly reduce the stereo separation. The
THB122 module contains the variable 10 kHz notch filter. This
module can be replaced with discrete components as shown
in Figure 8, using 1% resistors and 5% capacitors.
Some manufacturers add a PIN diode attenuator at the
antenna input. An example is shown in Figure 7.
The WB AGC sensitivity can be adjusted by changing R4
in series with the WB AGC input, Pin 1. The internal input
resistance is 15 k.
R15, R17 and R19 are the blanker timing resistors. They
were setup for this circuit and can be changed if desired.
FL1 is a linear phase IF filter . We recommend a Gaussian
(rounded) filter, such as SFG or SFH for lower distortion and
better separation than one with a flatter amplitude response.
The SFG types of filters have poorer selectivity than the ones
with flat GDT (group delay time) so some compromise has
been made on adjacent channel selectivity.
The blanker can be disabled for testing by grounding the
blanker AGC on Pin 2 in the MC13027.
The blanker and mixer inputs must be biased from the
4.0 V regulator through a low dc resistance like the
secondary winding of the RF coil.
The receiver VCO operates at 4 times the local oscillator
frequency and is divided internally in the MC13027 so that
both the mixer input and the LO out is the same as in other
receivers. This receiver can be connected to an existing
synthesizer. For AM stereo, the synthesizer must have low
phase noise. The Motorola MC145173 is recommended. For
bench testing of this receiver, the Motorola MC145151
parallel input synthesizer may be useful. It will operate on
9.0 V and the phase detector can provide tuning voltage
without a buffer amplifier.
The SS (stop–sense) output can be used for station
searching and scanning. The best way to use it is to connect
the SS signal to a comparator or A–D converter in the control
microprocessor. If Pin 23 is grounded during searching by
turning on Q3, the SS voltage changes from less than 0.5 V
to around 2.2 V when an RF threshold is exceeded, as is
shown in the graph in Figure 15. This system results in very
reliable stopping on usable signals and fast detection of AM
stereo signals. After a station is detected, Q3 should be
turned off.
This receiver is very easy to set up because the TOKO
module is pre–aligned. The only adjustments are to tune T1
and T2 for maximum voltage of the SS out line or maximum
audio with a weak signal. If desired, they can be changed
slightly to maximize stereo separation.
If different components are used, the blanker resistors can
be setup as follows:
Ground Pin 2 of the MC13027. Apply a 1.0 µs pulse or 50
Hz square wave of about 10 mV through a dummy antenna
and synchronize an oscilloscope to the pulse generator.
Observe the signal at the mixer collector (Pin 11). It should be
a sine wave burst. Remove the ground on Pin 2 and adjust
R15 so the burst is just suppressed. Check the performance
at the ends and middle of the band because the width might
change due to RF circuit bandwidth.
Mix the pulse signal with a CW signal of about 300 µV with
a power combiner and connect the oscilloscope to Pin 7 or
Pin 14 of the MC13122. Adjust R17 so the blanking starts at
the beginning of the audio pulse and R19 so the audio
blanking is just long enough to suppress the audio pulse. The
audio blanking time should not be made longer than
necessary because it will be more noticeable in the normal
program. The effectiveness of the blanker can be determined
in field testing by connecting a switch from Pin 2 of the
MC13027 to ground and bringing it outside the radio.
Figures 10 to 19 refer to the performance of the
Application Circuit of Figure 6.
MC13027 MC13122
19
MOTOROLA ANALOG IC DEVICE DATA
Figure 6.
A7NRES–T1370Y
T2
450 kHz
V
CC
WH8
Gnd
WH9
C27C1
R18
C26
R16
C25
C33
R26
R12
C29
Gnd
R AF OutL AF Out
LO Out
R6
R18
R9
C19
R3
Q2
R2
R21
C13
C11
C18
1234567
8
VT
R22
201918171615141312
11
123456789
10
65432
1
28272625242322212019181716
15
123456789
1011121314
I Det
L–R Det
Q Det
V
Loop Filt
Blend
Gnd
Pil Ind
Osc Out
Osc In
Pil Det I
Pil I
Pil Q
A Blk
E Det
Det In
3.0 V Reg
AGC
IF InSSL Out
L Filt In
L Filt Ctr
L Mat Out
R Mat Out
R Filt Ctr
R Filt In
R Out
WB AGC I
Blk AGC
Blk FB
4.0 V Reg
RF Gnd
Mix/Blk In
4.0 V FiltVLO
LO Out
WB AGC O
AFT
AF Blk
Delt
IF Out
R Filt
IF In
IF Gnd
RF Blk
Mix Out
Ch2 Out
Ch2 Cont
Ch2 In
Ch1 In
Ch1 Cont
Ch1 Out
RF Col
RF V
Gnd
Mixer In
Mixer Bias
VT
Osc
Osc Bias
Ant Gnd
Ant
C6
R19
R17
R15
C12
FL1
R4
Q1
1
3
L1
MPS6515
C
E
B
22 F
µ
C8
1.0 F
µ
470
Ω
3309
D
S
G
0.01
100 k
3.0 mH
R1
100
Ω
C7
1.0 F
µ
CC
FL2
TMG522E
120
Ω
15 k
0.01
CC
MC13122
IC2
MC13027
IC1
FL3
THB122
R7
22 k
C22
47 F
µ
C35
100 F
µ
R8
12 k
1.0 n
C28
1.0 n 1.0 n
0.01
3.3 k
C9
0.1
150 k
33 k
680 k
0.01
1.8 k
SFG450F
O
GI
C2
10 F
µ
C3 0.1
1.0 n
C5
47 F
µ
C14
10 F
µ
WH11 WH3
C15
0.1
1
3
2
6
4
A7NRES–11148N
T1
450 kHz
132
6
4
SS Out
WH5
2.2 k 2.2 k
R13
5.6 k
R14
5.6 k
.015 .015
WH4 WH6
1.0 n
C32
1.0 n
C21
0.1
100 k
C28 47 F
µ
C4 10 F
µ
R5
4.7 k
2.2 k
3.9 k
51
R20 1.0 k
C30
1.0 n
Stereo
CA
D1
X1
3.6 MHz
C18 22 F
µ
C34 1.0 n
C24 47 F
µ
C23 22 F
µ
C16
47 F
µ
C17
10 F
µ
C31
1.0 F
µ
R11
33 k
Search
WH7
WH10
Q3
MPS6515
C
E
G
WH12
AF Blk
CC
Figure 6. AMAX Chipset Application Circuit
10
Ω
AF Blk
WH13
WH2
WH1
MC13027 MC13122
20
MOTOROLA ANALOG IC DEVICE DATA
Figure 7. RF Pin Diode
Figure 8. MC13027/MC13122
Discrete RF and Notch Filters
Figure 9. Overall Selectivity of a Typical Receiver
versus Filter Control Voltage
C57
0.01
C7
0.01
R51
820
R5
2.7 k
R6
27 k
Q25
MMBT3906L
Q2
MMBT3904L
R8
220
C18
0.1
C6
0.47
C5
68
µ
F
R13
13 k
C14
0.01
RF In
AGC
BA585
D1
PIN
C56
0.047
R52
390
R4
82
R3
100 k
C8
0.047
Q1
MMBFJ309L
R7
3.3 k
1
WB AGC In
MC13027
2
AGC
L1
126ANS
7594HM
1
3
–60
OVERALL RESPONSE (dB)
AUDIO FREQUENCY (kHz)
0
–10
–20
–30
–40
–50
–70
–80
1.5 2.0 3.0 4.0 5.0 6.0 8.0 10 15 20 30
V at Pin 6 = 3.5 Vdc
2.5 Vdc
1.5 Vdc
–– Response at
–– Pins 10 and 11 Due
–– to IF Selectivity
–– Total Response at
–– Output Pins 7 and 14
8 (13)
9 (12)
10 (11)
720
44.2 k
44.2 k
22.1 k
360
360
MC13122 Pins
Filt In
Filt Ctr
Filt Out
IF/Audio Response at
Filter Input
+
WB AGC Out
20
MC13027 MC13122
21
MOTOROLA ANALOG IC DEVICE DATA
60
4.0
SS, STOP–SENSE, PIN 6 (V)
RF INPUT LEVEL (dBµV)
3.0
2.0
1.0
0
70 80 90 100 110
20
500
AF OUTPUT (mV)
ANTENNA INPUT (dBµV)
400
300
200
100
0
30 40 50 60 70 80
20
0
5.0 kHz ATTENUATION (dB)
ANTENNA INPUT (dBµV)
–5.0
–10
–15
–20
–25
30 40 50 60 70 80
20
50
400 Hz S/N (dB)
ANTENNA INPUT (dBµV)
42
34
26
18
10
30 40 50 60 70 80
20
40
SEPARATION (dB)
ANTENNA INPUT (dBµV)
30 40 50 60 70 80
32
24
16
8.0
0
20
4.0
BLEND VOLTAGE, PIN 23 (V)
ANTENNA INPUT (dBµV)
30 40 50 60 70 80
3.0
2.0
1.0
0
Figure 10. Blend Voltage versus RF Input Level Figure 11. Separation versus RF Input Level
Figure 12. Signal to Noise versus RF Input Level
Figure 13. 5.0 kHz Attentuation
versus RF Input Level
Figure 14. Audio Output Level
versus RF Input Level
Figure 15. Stop–Sense Voltage
versus RF Input Level
NOTE: The graphs on this page were made using the 15/60 pF
dummy antenna and the Application Circuit of Figure 6.
NOTE: The radio stays in mono until the stereo signal is
sufficiently large and then makes a smooth transition to
stereo. This is similar to FM receivers with variable
blend.
NOTE: The slightly abrupt change at around 25 dBµV is due
to the decoder switching into stereo.
NOTE: This curve shows the effect of the variable audio
bandwidth control of the MC13122. It is due to the
variable loading of the IF coil and the variable 10 kHz
notch filter in the output.
NOTE: All the curves of performance versus RF input level
were generated using the car radio receiver circuit
shown in Figure 6. Using a 15/60 pF dummy antenna
input and a 50% L only stereo signal.
NOTE: This measurement was made on the MC13122 alone
with a 10 k series input resistor. It will enable the
designer to determine the stop–sense level if the gain
of receiver RF section is known. Note that if Pin 23 is
held low, the SS voltage on Pin 6 rises from about 0.3
to 2.2 V over a small change in RF level. This can be
used to generate a very reliable stop signal. If Pin 23 is
not held low, the SS voltage starts out at 2.2 V and
rises slowly to a maximum of around 4.0 V.
Pin 23 = Open
Pin 23 = Grounded
MC13027 MC13122
22
MOTOROLA ANALOG IC DEVICE DATA
0
9.0
AGC VOLTAGE (V)
RF LEVEL INTO PIN 1 (mV)
8.0
6.0
4.0
2.0
0
1.0 2.0 3.0 4.0 5.0 6.0
7.0
5.0
3.0
1.0
10
1000
R19 (k
Ω
)
100
10
1.0
33 100 330 1000
10
1000
AF BLANKING TIME (
R15 (kΩ)
100
10
1.0
33 100 330 1000
10
1000
AF BLANKING DELAY (
R17 (kΩ)
100
10
1.0
33 100 330 1000
Figure 16. Audio Blanking Delay versus R17 Figure 17. RF Blanking Time versus R15
Figure 18. Audio Blanking Time versus R19
Figure 19. WB AGC Output Voltage (Pin 20)
versus RF Input Level
NOTE: This was measured by applying an RF signal through
a capacitor directly to Pin 1. The input resistance is
15 k, so the desired threshold can be increased by
adding a resistor in series with the input.
µ
s)
µ
s)AF BLANKING TIME (
µ
s)
MC13027 MC13122
23
MOTOROLA ANALOG IC DEVICE DATA
AMAX STEREO CHIPSET
The RF Module
In the early development phase of this AMAX Stereo
Chipset, Motorola worked with TOKO America Inc. to
develop an RF tuning module. Part number TMG522E was
assigned and is available from TOKO now. This module
provides the “tracked” tuning elements for the RF (T1 and T2
and associated capacitors and varicaps) and the VCO (T3 et
al). Some radio designers may prefer to develop their own
tuning system using discrete coils and components, but the
TOKO approach offers good performance, compactness and
ease of application. Motorola recommends that every
designer use this approach at least for initial system
development and evaluation.
As refinement of the application progressed, it was found
that a modification of the TMG522E was needed which would
reduce the amount of VCO leakage into the Mixer through the
power supply connections. This modification is described
below. Motorola will work with TOKO to develop a new part
number incorporating this change. In the meantime, it is
necessary that the user perform these simple changes,
because the radio circuits throughout this data sheet assume
this modified design.
Modifying the TMG522E
Referring to Figures 20 and 21, there are three simple
steps to the modification:
1. Cut the thin copper trace from Pin 2 to Pin 5 as shown.
2. Cut the thin copper trace from Pin 8 to the bottom of the
120 Ω resistor. Removal of the resistor is optional.
3. Connect a wire from Pin 5 to the top of the 120 Ω resistor
(or the upper pad for the resistor).
Figure 20. TMG522E Schematic
Figure 21. TMG522E Physical Modifications
Add Wire (3)
Cut (1)Cut (2)
1
2
487
536
47 k
47 k
10 k
T1
T2
T3
1203.9 k
Cut Trace (1)
X
X
Cut
Trace (2)
Add
Wire (3)
+B Gnd VT
RF Out Osc
Low
Osc
High
5
3.0 V
RF In
TMG522E
87654321
TMG522E
Add Wire (3)
Cut (1)
Cut (2)
87654321
MC13027 MC13122
24
MOTOROLA ANALOG IC DEVICE DATA
Figure 22. AMAX Chipset Printed Circuit Board
(Top View)
WH6
VT
Osc
+
+
+
+
+
+
+
+
+
+
+
+
C14
C5
C2
C11
C22 C35
WH11 WH3
FL2
L1
WH1 WH2
Gnd Ant
Q1
Q2
Q3
WH7
Search
C24
C23
C4
Gnd
T2
T1
FL1
WH4
L
FL3
WH5
WH12
X1
C18
C31
WH10
Gnd
C16
C20
C17
RSS
WH13
V
CC
+
C30
R12
R20
C29
R26
C34
IC2
R11
C28
C27
C1
R10
R8
R7
C8R3R1C7R2
C6
C13
IC1
R19
R17
C19
R5
C32
C33
R16
R13
C25
C12
C9R9
R15
R21
C10
R22
C15
C3
R4
C26
R14
R18
C21
R6
Figure 23. AMAX Chipset Printed Circuit Board
(Bottom View)
WH9
WH8
D1
MC13027 MC13122
25
MOTOROLA ANALOG IC DEVICE DATA
Figure 24. AMAX Chipset Printed Circuit Board
(Copper View)
MC13027 MC13122
26
MOTOROLA ANALOG IC DEVICE DATA
P SUFFIX
PLASTIC PACKAGE
CASE 738–03
ISSUE E
OUTLINE DIMENSIONS
DW SUFFIX
PLASTIC PACKAGE
CASE 751D–04
(SO–20L)
ISSUE E
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSIONS A AND B DO NOT INCLUDE
MOLD PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.150
(0.006) PER SIDE.
5. DIMENSION D DOES NOT INCLUDE
DAMBAR PROTRUSION. ALLOWABLE
DAMBAR PROTRUSION SHALL BE 0.13
(0.005) TOTAL IN EXCESS OF D DIMENSION
AT MAXIMUM MATERIAL CONDITION.
–A–
–B–
20
1
11
10
S
A
M
0.010 (0.25) B
S
T
D20X
M
B
M
0.010 (0.25)
P10X
J
F
G
18X
K
C
–T–
SEATING
PLANE
M
R
X 45
_
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A 12.65 12.95 0.499 0.510
B 7.40 7.60 0.292 0.299
C 2.35 2.65 0.093 0.104
D 0.35 0.49 0.014 0.019
F 0.50 0.90 0.020 0.035
G 1.27 BSC 0.050 BSC
J 0.25 0.32 0.010 0.012
K 0.10 0.25 0.004 0.009
M 0 7 0 7
P 10.05 10.55 0.395 0.415
R 0.25 0.75 0.010 0.029
__
__
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION L TO CENTER OF LEAD WHEN
FORMED PARALLEL.
4. DIMENSION B DOES NOT INCLUDE MOLD
FLASH.
M
L
J 20 PL
M
B
M
0.25 (0.010) T
DIM MIN MAX MIN MAX
MILLIMETERSINCHES
A 25.66 27.171.010 1.070
B 6.10 6.600.240 0.260
C 3.81 4.570.150 0.180
D 0.39 0.550.015 0.022
G 2.54 BSC0.100 BSC
J 0.21 0.380.008 0.015
K 2.80 3.550.110 0.140
L 7.62 BSC0.300 BSC
M 0 15 0 15
N 0.51 1.010.020 0.040
____
E
1.27 1.770.050 0.070
1
11
10
20
–A–
SEATING
PLANE
K
N
FG
D
20 PL
–T–
M
A
M
0.25 (0.010) T
E
B
C
F
1.27 BSC0.050 BSC
MC13027 MC13122
27
MOTOROLA ANALOG IC DEVICE DATA
P SUFFIX
PLASTIC PACKAGE
CASE 710–02
ISSUE B
OUTLINE DIMENSIONS
DW SUFFIX
PLASTIC PACKAGE
CASE 751F–04
(SO–28L)
ISSUE E
MIN MINMAX MAX
MILLIMETERS INCHES
DIM
A
B
C
D
F
G
J
K
M
P
R
17.80
7.40
2.35
0.35
0.41
0.23
0.13
0
°
10.05
0.25
18.05
7.60
2.65
0.49
0.90
0.32
0.29
8
°
10.55
0.75
0.701
0.292
0.093
0.014
0.016
0.009
0.005
0
°
0.395
0.010
0.711
0.299
0.104
0.019
0.035
0.013
0.011
8
°
0.415
0.029
1.27 BSC 0.050 BSC
NOTES:
1. DIMENSIONING AND TOLERANCING PER
ANSI Y14.5M, 1982.
2. CONTROLLING DIMENSION: MILLIMETER.
3. DIMENSION A AND B DO NOT INCLUDE MOLD
PROTRUSION.
4. MAXIMUM MOLD PROTRUSION 0.15
(0.006) PER SIDE.
5. DIMENSION D DOES NOT INCLUDE
DAMBAR PROTRUSION.
ALLOWABLE
DAMBAR PROTRUSION SHALL BE 0.13
(0.005) TOTAL IN EXCESS OF D
DIMENSION AT MAXIMUM MA TERIAL
CONDITION.
-A-
-B-
114
1528
-T-
C
SEATING
PLANE
0.010 (0.25)
B
M M
M
J
-T-
K
26X G
28X D
14X P
R
X 45°
F
0.010 (0.25) T A B
M
S S
NOTES:
1. POSITIONAL TOLERANCE OF LEADS (D), SHALL
BE WITHIN 0.25 (0.010) AT MAXIMUM MATERIAL
CONDITION, IN RELATION TO SEATING PLANE
AND EACH OTHER.
2. DIMENSION L TO CENTER OF LEADS WHEN
FORMED PARALLEL.
3. DIMENSION B DOES NOT INCLUDE MOLD FLASH.
1
SEATING
PLANE
15
14
28
M
A
B
K
C
N
F
G
D
H
J
L
DIM MIN MAX MIN MAX
INCHESMILLIMETERS
A 36.45 37.21 1.435 1.465
B 13.72 14.22 0.540 0.560
C 3.94 5.08 0.155 0.200
D 0.36 0.56 0.014 0.022
F 1.02 1.52 0.040 0.060
G 2.54 BSC 0.100 BSC
H 1.65 2.16 0.065 0.085
J 0.20 0.38 0.008 0.015
K 2.92 3.43 0.115 0.135
L 15.24 BSC 0.600 BSC
M 0 15 0 15
N 0.51 1.02 0.020 0.040
____
MC13027 MC13122
28
MOTOROLA ANALOG IC DEVICE DATA
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