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MAX2402EAP
Datasheet
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Maxim MAX2402EAP Datasheet

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_______________General Description
The MAX2402 transmitter integrates a double-balanced mixer, buffered local oscillator (LO) port, variable gain stage, and power amplifier into a single IC. It is intend­ed for use in the 800MHz to 1000MHz band, and is compatible with both direct-sequence and frequency­hopping spread-spectrum designs in the 902MHz to 928MHz ISM band.
A shutdown function reduces the current draw to less than 2µA in less than 10µs. The MAX2402 comes in a 20-pin SSOP package to minimize board area.
________________________Applications
Direct-Sequence Spread-Spectrum Transmitter Frequency-Hopping Spread-Spectrum
Transmitter FSK, GMSK, BPSK, and ASK Digital Transmitter AM and FM Analog Transmitter
____________________________Features
♦ Low-Cost, Flexible Transmitter ♦ More than 100mW of Output Power into 50Ω ♦ Operates from 800MHz to 1000MHz ♦ Single +5V Supply ♦ 20-Pin SSOP Package ♦ Uses Less than 2µA in Power-Down ♦ More than 35dB of Power Adjustment Range ♦ LO Input Power Range from -6dBm to +6dBm ♦ 2V Linear Range on Modulation Input
MAX2402
800MHz to 1000MHz Transmitter
________________________________________________________________
Maxim Integrated Products
1
20 19 18 17 16 15 14 13
1 2 3 4 5 6 7 8
GND V
CC
GND GND
V
CC
GND
MOD
VGC
TOP VIEW
OUT GND OUT GNDGND
LO-
LO+
GND
12 11
9
10
V
CC
LGND
BADJ
SHDN
SSOP
MAX2402
__________________Pin Configuration
MOD
LO+ LO-
MODULATION
BUFFER
LO INPUT
BUFFER
MIXER
VGC
VGC
OUT
BADJ
SHDN
POWER
AMPLIFIER
MASTER BIAS
________________Functional Diagram
19-0392; Rev 1; 5/96
PART
MAX2402EAP* -40°C to +85°C
TEMP. RANGE PIN-PACKAGE
20 SSOP
EVALUATION KIT MANUAL
FOLLOWS DATA SHEET
______________Ordering Information
* An alternate marking, MAX2402CAP, has been identically tested.
For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800
MAX2402
800MHz to 1000MHz Transmitter
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
DC ELECTRICAL CHARACTERISTICS
(VCC= 4.75V to 5.5V, BADJ = open, SHDN = VCC- 0.5V, VGC = VCC, MOD = open, TA= -40°C to +85°C, unless otherwise noted.)
AC ELECTRICAL CHARACTERISTICS
(MAX2402 evaluation kit, VCC= 5.0V, BADJ = 2V, SHDN = VCC, MOD = 0V, VGC = VCC, R
LOAD
= 35Ω, fLO= 900MHz,
LO power = -3dBm, TA= -40°C to +85°C, unless otherwise noted.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
Note 1: See
Typical Operating Characteristics
graphs.
Note 2: Guaranteed by design.
V
CC
........................................................................-0.3V to +6.5V
Continuous Power Dissipation (T
A
= +70°C)
SSOP (derate 16.7mW/°C above +70°C) ......................1.33W
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range.............................-65°C to +160°C
Lead Temperature (soldering, 10sec).............................+300°C
SHDN
= 0.5V
Not transmitting
SHDN = V
CC
VGC = V
CC
MOD = V
CC
MOD = 0V
CONDITIONS
µA0.15 2I
CCPD
Shutdown Supply Current
mA105I
CC
Supply Current
VV
CC
- 0.5V
SHDN
HighSHDN High Threshold
V0.5V
SHDN
LowSHDN Low Threshold
µA10.5I
PD
SHDN Bias Current
V4.75 5.50V
CC
Supply Voltage Range
µA115I
VGC
VGC Input Bias Current
µA
325
I
MOD
MOD Bias Current
-320
UNITSMIN TYP MAXSYMBOLPARAMETER
fLO= 900MHz + 901MHz
(Note 1)
(Note 1)
MOD = 5Vp-p @ 100kHz
(Note 2)
(Note 2)
(Note 2)
For max power out (50Ω input term) (Note 2)
VGC = 0V (Note 1)
(Note 1)
CONDITIONS
dBm28.4IP3Output IP3 (BADJ = 1.0V)
dBC25HS33rd Harmonic Suppression
dBC22HS22nd Harmonic Suppression
dBC30CSCarrier Suppression
V1.0 2.5VGCVGC Control Range
MHz25MODBWMOD Usable Bandwidth
MHz800 1000f
LO
LO Frequency Range
dBm
dB24P
GAIN
Power Gain from LO
dBm-19P
MIN
Minimum Output Power
dBm21P
MAX
Maximum Output Power
UNITSMIN TYP MAXSYMBOLPARAMETER
P
OUT
= 20dBm (including current to load) mA165I
CCAC
Supply Current
-6 6P
LO
LO Input Power Range
MAX2402
800MHz to 1000MHz Transmitter
_______________________________________________________________________________________
3
25 20
-25
1.0 2.5
OUTPUT POWER vs.
GAIN CONTROL VOLTAGE
15 10
0
-10
-20
MAX2402 TOC 1
VGC (V)
OUTPUT POWER (dBm)
-5
-15
1.5
5
2.0
25
23
800 820 840 880 900 940 980
OUTPUT POWER vs. FREQUENCY
vs. TEMPERATURE
21
19
15
MAX2402 TOC 2
FREQUENCY (MHz)
OUTPUT POWER (dBm)
860
17
920 960
+85°C
+24°C
-40°C
22.0
-50 -30 -10 30 90
OUTPUT POWER vs.
TEMPERATURE
21.5
21.0
20.0
MAX2402 TOC 3
TEMPERATURE (°C)
OUTPUT POWER (dBm)
20.5
10 50 70
900MHz INPUT
25 23 21
012 4
OUTPUT POWER vs. BIAS CONTROL VOLTAGE
vs. FREQUENCY
19 17 15 13
7
MAX2402 TOC 4
BADJ VOLTAGE (V)
OUTPUT POWER (dBm)
11
9
35
800MHz
900MHz
990MHz
260 240
012 4
SUPPLY CURRENT vs. BIAS CONTROL VOLTAGE
vs. FREQUENCY
220 200 180 160
100
MAX2402 TOC 5
BADJ VOLTAGE (V)
SUPPLY CURRENT (mA)
140 120
35
800MHz
900MHz
990MHz
39 37
0.5 1.0 1.5 2.5
OUTPUT POWER LEVEL OF
2nd AND 3rd HARMONICS OF LO
(LO = 900MHz, -3dBm, MOD = 5V)
35 33 31 29
23 21 19 17 15 13
MAX2402 TOC 6
BADJ VOLTAGE (V)
OUTPUT POWER BELOW FUNDAMENTAL (dBC)
27 25
2.0 4.0
TA = -40°C
3.0 3.5
3rd HARMONIC
TA = +24°C
TA = +85°C
TA = -40°C
TA = +24°C
TA = +85°C
2nd HARMONIC
38
1.0 1.5 2.0 3.0
AMPLITUDE OF 3rd & 5th HARMONICS
OF MODULATED WAVEFORM
(100kHz SINEWAVE MODULATION OF 900MHz LO)
34
42
30
22 18 14 10
MAX2402 TOC 7
MODULATION VOLTAGE, PEAK-TO-PEAK (V)
OUTPUT POWER (dBC) BELOW 900.1MHz
26
2.5 5.0
TA = -40°C
3.5 4.0 4.5
900.5MHz
TA = +24°C
TA = +85°C
TA = -40°C
TA = +24°C
TA = +85°C
900.3MHz
__________________________________________Typical Operating Characteristics
(MAX2402 evaluation kit, VCC= 5.0V, BADJ = 2V, SHDN = VCC, MOD = 0V, VGC = VCC, R
LOAD
= 35Ω, fLO= 900MHz,
LO power = -3dBm)
_______________Detailed Description
The MAX2402 transmitter is a versatile design that inte­grates several RF functions on a single IC. It has a wide variety of applications in portable and stationary wire­less designs. Each of the functional blocks (shown in the
Functional Diagram
) is described in detail in the fol-
lowing sections.
LO Inputs
The LO inputs are internally capacitively coupled and self biasing. The LO port can be driven differentially or single ended. When terminated at the LO inputs with 50Ω, the transmitter will provide full output power for LO inputs from -6dBm to +6dBm with single-ended drive, and -12dBm to +6dBm with differential drive. Input power beyond this range may saturate the LO input buffer, while input power below this range may result in less output power. The limiter is two cascaded differen­tial stages, which also isolates the LO input from the mixer. This will help reduce any frequency-pulling effects in an external LO due to mixer loading. The lim­iter output drives one port of a double-balanced Gilbert mixer.
MOD Input
The mixer’s other port, the MOD input, remains linear over a 2V range from about 1.5V to 3.5V at the input. When driven with digital modulation (0V to 5V), this port will completely limit, resulting in a hard BPSK­modulated signal. Since this input is self biasing, carrier suppression can be improved by externally capacitively coupling the signal into the port (the MOD input resis­tance is approximately 10kΩ). This would compensate for voltage offset or duty-cycle offset at this port, thus increasing carrier suppression. This MOD self bias is designed for very low on-chip offset, resulting in excel­lent carrier suppression. Since this port self biases when the signal is removed from MOD, the mixer will attenuate the output power by about 40dB, resulting in further attenuation past that attained from VGC con­trol—a useful feature for ASK modulation.
VGC Stage
The mixer output drives the VGC stage. This stage attenuates through a multiplication technique that does not distort the signal with increased attenuation. VGC control is nonattenuating when connected to the V
CC
supply. VGC will attenuate for voltages from 2.5V to
1.0V. Most attenuation occurs between 1V and 2V. Maximum attenuation is achieved below 0.8V. Typical maximum attenuation is 40dB. At or beyond 40dB of attenuation, the signal may be slightly nonmonotonic. This means that there may be a slight upturn in the sig­nal level at the low end of the VGC control range (typi­cally about 1dB). Because of the stability implications, we suggest that the user not plan on attenuating past 35dB within a feedback loop.
Power Amplifier
The VGC stage passes the signal to the power amplifi­er. This class AB stage will produce at least 20dBm of output power for almost the complete transmit frequen­cy range (with TA= +25°C). See
Typical Operating
Characteristics
.
BADJ Input
The BADJ input adjusts the bias of the output stage. Increasing this voltage decreases bias current in the output devices, which increases efficiency, but also increases harmonic distortion (since the stage will be pushed further toward class B operation). Decreasing BADJ’s voltage increases bias current in the output devices, resulting in higher output power and less har­monic distortion. Be sure to optimize BADJ for your application.
MAX2402
800MHz to 1000MHz Transmitter
4 _______________________________________________________________________________________
_____________________Pin Description
NAME FUNCTION
1 VGC
Variable Gain Control Input. Connect to VCCfor maximum gain.
2 MOD Baseband Modulation Input to mixer
PIN
3, 5, 8,
13, 15, 17,
18, 20
GND Ground
4, 12, 19 V
CC
Supply Voltage, set between 4.75V and 5.5V
10 BADJ
Bias Adjustment Control for power amplifier. Connect resistor from BADJ to V+ or GND (see Table 1).
9 SHDN
Shutdown Control Input. Low level = off, high level = on.
7 LO- Local-Oscillator Negative Input
6 LO+ Local-Oscillator Positive Input
14, 16 OUT Power-Amplifier Output
11 LGND
Connect 27nH inductor from LGND to GND to maximize output power.
BADJ can be left open or adjusted with a single pull­up or pull-down resistor to VCCor GND, respectively. The value of this resistor determines the amount of adjustment applied. A single resistor results in no cur­rent flow at BADJ during power-down (whereas a resistor divider always has current flowing through the resistors). Table 1 shows the approximate bias adjust voltage at the pin for different resistor values. At lower LO frequencies, where the transmitter gain and output power is the highest, setting BADJ to a low voltage (maximum bias current) causes excessive current in the output and can cause unstable behavior in the IC. At lower LO frequencies (around 800MHz), more than 22dBm of power is easily obtained with BADJ set for 3V or more. If higher bias current and less distortion is desired in the 800MHz range, using a lower inductor value on LGND (pin 11) (see the
Typical Application
Circuit
) might make the desired bias level stable. At higher frequencies (near 1000MHz), a lower bias level voltage results in more power (see the Output Power vs. Bias Control Voltage vs. Frequency graph in the
Typical
Operating Characteristics
).
Power Amplifier Output
The power amplifier has an open-collector output that can drive into a load of 30Ω to 50Ω; however, maximum power transfer is obtained at about 35Ω. 27nH to ground is recommended on LGND (pin 11), as shown in the
Typical Application Circuit
. This inductor is used as a current source on the base of the output stage to pull stored charge out of the base.
SHDN Input
The SHDN input completely shuts down the current from the supply and all signal pins when switched below 0.5V. During normal operation, SHDN should remain above VCC- 0.5V.
The shutdown control shuts down the total current to below 150nA (typ). Power-up occurs within 10µs.
__________Applications Information
The MAX2402 transmitter operates within the 800MHz to 1000MHz frequency range. Figure 1 shows a typical application circuit. Additional applications information can be obtained from the MAX2402 evaluation kit manual.
MAX2402
800MHz to 1000MHz Transmitter
_______________________________________________________________________________________ 5
Resistor
Value (Ω)
BADJ with Resistor
Connected to GND (V)*
BADJ with Resistor
Connected to VCC(V)
10k 0.36 4.54 20k 0.63 4.27 30k 0.84 4.05 40k 1.00 3.89
50k 1.13 3.75 100k 1.54 3.34 200k 1.89 3.00 300k 2.05 2.85 400k 2.13 2.75 500k 2.20 2.68
1M 2.31 2.57
Figure 1. Typical Application Circuit
MAX2402
BADJ
300k
50Ω
39pF
50Ω
27nH
SHDN
GND
LO-
LO+
GND
V
CC
V
CC
GND
MOD
VGC
LGND
V
CC
GND
OUT
GND
VCO
MODULATION
SHUTDOWN
CONTROL
VARIABLE
GAIN CONTROL
OUT
GND
GND
V
CC
GND
39pF
47nH
V
CC
V
CC
39pF 0.01µF
V
CC
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
Table 1. Bias-Adjust Voltage for Various Resistor Values
* Typical variation of BADJ over temperature and process is
less than 5%.
MAX2402
800MHz to 1000MHz Transmitter
6 _______________________________________________________________________________________
________________________________________________________Package Information
L
DIM
A
A1
B C D E e H L
α
MIN
0.068
0.002
0.010
0.005
0.278
0.205
0.301
0.022
0˚
MAX
0.078
0.008
0.015
0.009
0.289
0.212
0.311
0.037
8˚
MIN
1.73
0.05
0.25
0.13
7.07
5.20
7.65
0.55
0˚
MAX
1.99
0.21
0.38
0.22
7.33
5.38
7.90
0.95
8˚
INCHES MILLIMETERS
α
20-PIN SSOP
SHRINK
SMALL OUTLINE
PACKAGE
HE
D
A
A1
C
0.127mm
0.004in.
B
0.65 BSC0.0256 BSC
21-0003A
e
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