Output frequency range: 1500 MHz to 2500 MHz
Modulation bandwidth: >500 MHz (3 dB)
1 dB output compression: 14 dBm @ 1900 MHz
Noise floor: −158 dBm/Hz
Sideband suppression: −45 dBc @ 1900 MHz
Carrier feedthrough: −45 dBm @ 1900 MHz
Single supply: 4.75 V to 5.25 V
24-lead LFCSP_VQ
APPLICATIONS
Cellular communication systems
CDMA2000/GSM/WCDMA
WiMAX/broadband wireless access systems
Satellite modems
GENERAL DESCRIPTION
The ADL5372 is a member of the fixed-gain quadrature modulator
(F-MOD) family designed for use from 1500 MHz to 2500 MHz.
Its excellent phase accuracy and amplitude balance enable high
performance intermediate frequency or direct radio frequency
modulation for communication systems.
The ADL5372 provides a >500 MHz, 3 dB baseband bandwidth,
making it ideally suited for use in broadband zero IF or low
IF-to-RF applications and in broadband digital predistortion
transmitters.
Quadrature Modulator
ADL5372
FUNCTIONAL BLOCK DIAGRAM
IBBP
IBBN
LOIP
LOIN
QBBN
QBBP
The ADL5372 accepts two differential baseband inputs and a
single-ended, local oscillator (LO) and generates a singleended output.
The ADL5372 is fabricated using the Analog Devices, Inc.
advanced silicon-germanium bipolar process. It is available in
a 24-lead, exposed-paddle, Pb-free, LFCSP. Performance is
specified over a −40°C to +85°C temperature range. A Pb-free
evaluation board is available.
QUADRATURE
PHASE
SPLITTER
Figure 1.
VOUT
06511-001
Rev. 0
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Anal og Devices for its use, nor for any infringements of patents or ot her
rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
VS = 5 V; TA = 25°C; LO = 0 dBm1 single-ended; baseband I/Q amplitude = 1.4 V p-p differential sine waves in quadrature with a 500 mV
dc bias; baseband I/Q frequency (f
Table 1.
Parameter Conditions Min Typ Max Unit
OPERATING FREQUENCY RANGE Low frequency 1500 MHz
High frequency 2500 MHz
LO = 1900 MHz
Output Power VIQ = 1.4 V p-p differential 7.1 dBm
Output P1dB 14.2 dBm
Carrier Feedthrough −45 dBm
Sideband Suppression −45 dBc
Quadrature Error 0.21 Degrees
I/Q Amplitude Balance 0.09 dB
Second Harmonic P
Third Harmonic P
Output IP2 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Output IP3 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Noise Floor
GSM 6 MHz carrier offset, P
WCDMA
LO = 2150 MHz
Output Power VIQ = 1.4 V p-p differential 7.2 dBm
OutputP1dB 14 dBm
Carrier Feedthrough −41 dBm
Sideband Suppression −44 dBc
Quadrature Error 0.27 Degrees
I/Q Amplitude Balance 0.12 dB
Second Harmonic P
Third Harmonic P
Output IP2 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Output IP3 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Noise Floor
WCDMA
LO = 2400 MHz
Output Power VIQ = 1.4 V p-p differential 5.6 dBm
OutputP1dB 12.4 dBm
Carrier Feedthrough −36 dBm
Sideband Suppression −40 dBc
Quadrature Error 0.6 Degrees
I/Q Amplitude Balance 0.13 dB
Second Harmonic P
Third Harmonic P
Output IP2 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Output IP3 f1BB = 3.5 MHz, f2BB = 4.5 MHz, P
Noise Floor
WiMAX
) = 1 MHz, unless otherwise noted.
BB
− (fLO + (2 × fBB)), P
OUT
− (fLO + (3 × fBB)), P
OUT
= 6.2 dBm −50 dBc
OUT
= 6.2 dBm −47 dBc
OUT
= 1 dBm per tone 54 dBm
OUT
= 1 dBm per tone 27 dBm
OUT
I/Q inputs = 0 V differential with a 500 mV common-mode bias,
20 MHz carrier offset; LO = 1960 MHz
= 5 dBm, PLO = 6 dBm; LO = 1960 MHz −158 dBc/Hz
OUT
Single carrier, 20 MHz carrier offset, P
P
= 0 dBm; LO = 1966 MHz
LO
− (fLO + (2 × fBB)), P
OUT
− (fLO + (3 × fBB)), P
OUT
= 6.2 dBm −59 dBc
OUT
= 6.2 dBm −48 dBc
OUT
OUT
OUT
= −10 dBm,
OUT
= 1 dBm per tone 65 dBm
= 1 dBm per tone 26.5 dBm
I/Q inputs = 0 V differential with a 500 mV common-mode bias,
20 MHz carrier offset
Single carrier, 20 MHz carrier offset, P
= −10 dBm, PLO = 0 dBm;
OUT
LO = 2140 MHz
− (fLO + (2 × fBB)), P
OUT
− (fLO + (3 × fBB)), P
OUT
= 6.2 dBm −54 dBc
OUT
= 6.2 dBm −48 dBc
OUT
= 1 dBm per tone 57 dBm
OUT
= 1 dBm per tone 24.5 dBm
OUT
I/Q inputs = 0 V differential with a 500 mV common-mode bias,
20 MHz carrier offset; LO = 2350 MHz
I and Q Input Bias Level 500 mV
Input Bias Current Current sourcing from each baseband input with a bias of 500 mV dc2 45 μA
Input Offset Current 0.1 μA
Differential Input Impedance 2900 kΩ
Bandwidth (0.1 dB) LO = 1900 MHz, baseband input = 700 mV p-p sine wave on 500 mV dc 70 MHz
Bandwidth (1 dB) LO = 1900 MHz, baseband input = 700 mV p-p sine wave on 500 mV dc 350 MHz
POWER SUPPLIES Pin VPS1 and Pin VPS2
Voltage 4.75 5.25 V
Supply Current 165 mA
1
High LO drive reduces noise at a 6 MHz carrier offset in GSM applications.
2
See V-to-I Converter section for architecture information.
1
Characterization performed at typical level −6 0 +6 dBm
Rev. 0 | Page 4 of 24
Page 5
ADL5372
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Supply Voltage VPOS 5.5 V
IBBP, IBBN, QBBP, QBBN 0 V to 2 V
LOIP and LOIN 13 dBm
Internal Power Dissipation 1100 mW
θJA (Exposed Paddle Soldered Down) 54°C/W
Maximum Junction Temperature 150°C
Operating Temperature Range −40°C to +85°C
Storage Temperature Range −65°C to +150°C
Stresses above those listed under Absolute Maximum Ratings
may cause permanent damage to the device. This is a stress
rating only; functional operation of the device at these or any
other conditions above those indicated in the operational
section of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect
device reliability.
ESD CAUTION
Rev. 0 | Page 5 of 24
Page 6
ADL5372
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS
QBBP
COM4
QBBN
COM4
IBBN
IBBP
2422232120
19
COM1
COM1
VPS1
VPS1
VPS1
VPS1
1
2
3
4
5
6
F-MOD
TOP VIEW
(Not to Scale)
798
101112
LOIP
LOIN
COM2
COM2
COM3
VPS5
18
VPS4
17
VPS3
16
VPS2
15
VPS2
14
VOUT
13
COM3
06511-002
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Description
1, 2, 7, 10 to 12,
COM1 to COM4 Input Common Pins. Connect to ground plane via a low impedance path.
21, 22
3 to 6, 14 to 18 VPS1 to VPS5
Positive Supply Voltage Pins. All pins should be connected to the same supply (V
adequate external bypassing, connect 0.1 μF capacitors between each pin and ground.
Adjacent power supply pins of the same name can share one capacitor (see Figure 25).
8, 9 LOIP, LOIN
50 Ω Single-Ended Local Oscillator Input. Internally dc-biased. Pins must be ac-coupled.
AC-couple LOIN to ground and drive LO through LOIP.
13 VOUT
Device Output. Single-ended RF output. Pin should be ac-coupled to the load. The output
is ground referenced.
19, 20, 23, 24 IBBP, IBBN, QBBN, QBBP
Differential In-Phase and Quadrature Baseband Inputs. These high impedance inputs
must be dc-biased to 500 mV dc and must be driven from a low impedance source.
Nominal characterized ac signal swing is 700 mV p-p on each pin. This results in a differential
drive of 1.4 V p-p with a 500 mV dc bias. These inputs are not self-biased and must be
externally biased.
Exposed Paddle Connect to ground plane via a low impedance path.
). To ensure
S
Rev. 0 | Page 6 of 24
Page 7
ADL5372
TYPICAL PERFORMANCE CHARACTERISTICS
VS = 5 V; TA = 25°C; LO = 0 dBm single-ended; baseband I/Q amplitude = 1.4 V p-p differential sine waves in quadrature with a 500 mV
dc bias; baseband I/Q frequency (f
Figure 17. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
vs. fBB and Temperature (fLO = 1900 MHz)
OUT
5
4.5
4
SSB OUTPUT POWER (dBm)
6511-017
SIDEBAND SUPPRESSION
–60
DISTORTION, CARRIER F EEDTHROUGH,
SECOND-ORDER DISTORTI ON, THIRD-ORDER
–70
SECOND ORDER (d Bc)
–6–4–20246
LO AMPLITUDE (dBm)
4
SSB OUTPUT P OWER (d Bm)
3
06511-020
Figure 20. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
vs. LO Amplitude (fLO = 1900 MHz)
OUT
Rev. 0 | Page 9 of 24
Page 10
ADL5372
–
20
SSB OUTP UT POW ER (dBm)
–30
–40
–50
SIDEBAND SUP PRESSI ON (dBc)
SIDEBAND SUPPRESSION
–60
DISTORTION, CARRIER FEEDTHROUGH,
SECOND-O RDER DISTORTIO N, THIRD-ORDER
–70
–6–4–20246
LO AMPLITUDE (dBm)
CARRIER
FEEDTHROUGH (dBm)
THIRD ORDER (dBc)
SECOND ORDER (dBc)
Figure 21. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
0.20
0.19
0.18
0.17
0.16
0.15
0.14
0.13
SUPPLY CURRENT (A)
0.12
0.11
0.10
–40–1510356085
vs. LO Amplitude (fLO = 2150 MHz)
OUT
VS = 5.25V
VS = 5V
VS = 4.75V
TEMPERATURE (° C)
Figure 22. Power Supply Current vs. Temperature
22
8
7
6
5
4
SSB OUTPUT POWER (dBm)
3
06511-021
20
18
16
14
12
10
QUANTITY
8
6
4
2
0
–159.1
–158.7
–158.9
NOISE AT 20M Hz OFFS ET (dBm/Hz )
–158.3
–158.5
–158.1
Figure 23. 20 MHz Offset Noise Floor Distribution at f
f
= 1960MHz
LO
–157.9
–157.7
–157.5
–157.3
= 1960 MHz
LO
–157.1
06511-023
(I/Q Amplitude = 0 mV p-p with 500 mV dc Bias)
06511-042
Rev. 0 | Page 10 of 24
Page 11
ADL5372
THEORY OF OPERATION
CIRCUIT DESCRIPTION
Overview
The ADL5372 can be divided into five circuit blocks: the LO
interface, the baseband voltage-to-current (V-to-I) converter,
the mixers, the differential-to-single-ended (D-to-S) stage, and
the bias circuit. A detailed block diagram of the device is shown
in
Figure 24.
LOIP
LOIN
IBBP
IBBN
QBBP
QBBN
The LO interface generates two LO signals in quadrature. These
signals are used to drive the mixers. The I and Q baseband input
signals are converted to currents by the V-to-I stages, which
then drive the two mixers. The outputs of these mixers combine
to feed the output balun, which provides a single-ended output.
The bias cell generates reference currents for the V-to-I stage.
LO Interface
The LO interface consists of a polyphase quadrature splitter
followed by a limiting amplifier. The LO input impedance is set
by the polyphase. The LO can be driven either single-ended or
differentially. When driven single-ended, the LOIN pin should
be ac grounded via a capacitor. Each quadrature LO signal then
passes through a limiting amplifier that provides the mixer with
a limited drive signal.
PHASE
SPLITTER
Σ
Figure 24. Block Diagram
OUT
6511-024
V-to-I Converter
The differential baseband inputs (QBBP, QBBN, IBBN, and
IBBP) consist of the bases of PNP transistors, which present a
high impedance. The voltages applied to these pins drive the
V-to-I stage that converts baseband voltages into currents. The
differential output currents of the V-to-I stages feed each of their
respective Gilbert-cell mixers. The dc common-mode voltage at
the baseband inputs sets the currents in the two mixer cores.
Varying the baseband common-mode voltage influences the
current in the mixer and affects overall modulator performance.
The recommended dc voltage for the baseband common-mode
voltage is 500 mV dc.
Mixers
The ADL5372 has two double-balanced mixers: one for the
in-phase channel (I-channel) and one for the quadrature
channel (Q-channel). Both mixers are based on the Gilbert-cell
design of four cross-connected transistors. The output currents
from the two mixers sum together into a load. The signal
developed across this load is used to drive the D-to-S stage.
D-to-S Stage
The output D-to-S stage consists of an on-chip balun that
converts the differential signal to a single-ended signal. The
balun presents high impedance to the output (VOUT). Hence, a
matching network may be needed at the output for optimal
power transfer.
Bias Circuit
An on-chip band gap reference circuit is used to generate a
proportional-to-absolute temperature (PTAT) reference current
for the V-to-I stage.
Rev. 0 | Page 11 of 24
Page 12
ADL5372
BASIC CONNECTIONS
Figure 25 shows the basic connections for the ADL5372.
QBBPQBBNIBBNIBBP
C16
VPOS
COM1
COM1
VPS1
VPS1
VPS1
VPS1
C12
0.1µF
1
2
3
4
5
6
GND
CLOP
100pF
QBBP
COM4
QBBN
COM4
2423222120
Z1
F-MOD
EXPOSED PADDLE
789
COM2
LO
LOIP
LOIN
101112
COM2
CLON
100pF
IBBN
COM3
COM3
IBBP
19
18
17
16
15
14
13
VPS5
VPS4
VPS3
VPS2
VPS2
VOUT
COUT
100pF
C13
0.1µF
0.1µF
C15
0.1µF
C14
0.1µF
C11
OPEN
VPOS
VOUT
Figure 25. Basic Connections for the ADL5372
Power Supply and Grounding
All the VPS pins must be connected to the same 5 V source.
Adjacent pins of the same name can be tied together and decoupled
with a 0.1 μF capacitor. These capacitors should be located as
close as possible to the device. The power supply can range
between 4.75 V and 5.25 V.
The COM1 pin, COM2 pin, COM3 pin, and COM4 pin should
be tied to the same ground plane through low impedance paths.
The exposed paddle on the underside of the package should also
be soldered to a low thermal and electrical impedance ground
plane. If the ground plane spans multiple layers on the circuit
board, they should be stitched together with nine vias under the
exposed paddle. The Application Note
AN-772 discusses the
thermal and electrical grounding of the LFCSP in detail.
06511-025
Baseband Inputs
The baseband inputs QBBP, QBBN, IBBP, and IBBN must be
driven from a differential source. The nominal drive level of
1.4 V p-p differential (700 mV p-p on each pin) should be
biased to a common-mode level of 500 mV dc.
The dc common-mode bias level for the baseband inputs may
range from 400 mV to 600 mV. This results in a reduction in
the usable input ac swing range. The nominal dc bias of 500 mV
allows for the largest ac swing, limited on the bottom end by the
ADL5372 input range and on the top end by the output compliance
range on most DACs from Analog Devices.
LO Input
A single-ended LO signal should be applied to the LOIP pin
through an ac coupling capacitor. The recommended LO drive
power is 0 dBm. The LO return pin, LOIN, should be ac-coupled
to ground through a low impedance path.
The nominal LO drive of 0 dBm can be increased to up to 6 dBm
to realize an improvement in the noise performance of the
modulator. This improvement is tempered by degradation in
the sideband suppression performance (see
Figure 20) and,
therefore, should be used judiciously. If the LO source cannot
provide the 0 dBm level, then operation at a reduced power
below 0 dBm is acceptable. Reduced LO drive results in slightly
increased modulator noise. The effect of LO power on sideband
suppression and carrier feedthrough is shown in
effect of LO power on GSM noise is shown in
Figure 20. The
Figure 35.
RF Output
The RF output is available at the VOUT pin (Pin 13). The
VOUT pin connects to an internal balun, which is capable of
driving a 50 Ω load. For applications requiring 50 Ω output
impedance, external matching is needed (see
Figure 8 for S22
performance). The internal balun provides a low dc path to
ground. In most situations, the VOUT pin should be ac-coupled
to the load.
Rev. 0 | Page 12 of 24
Page 13
ADL5372
–
–
OPTIMIZATION
The carrier feedthrough and sideband suppression performance
of the ADL5372 can be improved by using optimization
techniques.
Carrier Feedthrough Nulling
Carrier feedthrough results from minute dc offsets that occur
between each of the differential baseband inputs. In an ideal
modulator, the quantities (V
are equal to zero, which results in no carrier feedthrough. In a real
modulator, those two quantities are nonzero; and, when mixed
with the LO, they result in a finite amount of carrier feedthrough.
The ADL5372 is designed to provide a minimal amount of carrier
feedthrough. Should even lower carrier feedthrough levels be
required, minor adjustments can be made to the (V
and (V
QOPP
− V
) offsets. The I-channel offset is held constant
QOPN
while the Q-channel offset is varied until a minimum carrier
feedthrough level is obtained. The Q-channel offset required to
achieve this minimum is held constant, while the offset on the
I-channel is adjusted until a new minimum is reached. Through
two iterations of this process, the carrier feedthrough can be
reduced to as low as the output noise. The ability to null is
sometimes limited by the resolution of the offset adjustment.
Figure 26 shows the relationship of carrier feedthrough vs. dc
offset as null.
60
–64
–68
–72
–76
–80
CARRIER FEEDTHRO UGH (dBm)
–84
–88
–300 –240 –180 –120 –60060 120 180 240 300
Figure 26. Carrier Feedthrough vs. DC Offset Voltage at 1900 MHz
Note that throughout the nulling process, the dc bias for the
baseband inputs remains at 500 mV. When no offset is applied
= V
V
IOPP
V
IOPP
When an offset of +V
V
IOPP
V
IOPN
V
IOPP
= 500 mV, or
IOPN
− V
= V
IOPN
IOS
IOS
= 500 mV + V
= 500 mV − V
− V
= V
IOPN
IOS
The same applies to the Q channel.
− V
IOPN
) and (V
IOPP
VP – VN OFFSET (µV)
QOPP
IOPP
− V
− V
= 0 V
is applied to the I-channel inputs
/2, and
IOS
/2, such that
IOS
QOPN
IOPN
)
)
06511-045
It is often desirable to perform a one-time carrier null calibration. This is usually performed at a single frequency.
Figure 27
shows how carrier feedthrough varies with LO frequency over a
range of ±50 MHz on either side of a null at 1900 MHz.
Figure 27. Carrier Feedthrough vs. Frequency After Nulling at 1900 MHz
Sideband Suppression Optimization
Sideband suppression results from relative gain and relative
phase offsets between the I-channel and Q-channel and can
be suppressed through adjustments to those two parameters.
Figure 28 illustrates how sideband suppression is affected by
the gain and phase imbalances.
0
–10
2.5dB
–20
1.25dB
0.5dB
–30
0.25dB
–40
0.125dB
0.05dB
–50
0.025dB
–60
0.0125dB
–70
SIDEBAND SUPPRESSI ON (dBc)
0dB
–80
–90
0.010. 1110100
PHASE ERROR (Deg rees)
06511-028
Figure 28. Sideband Suppression vs. Quadrature Phase Error for
Various Quadrature Amplitude Offsets
Figure 28 underlines the fact that adjusting only one parameter
improves the sideband suppression only to a point, unless the
other parameter is also adjusted. For example, if the amplitude
offset is 0.25 dB, improving the phase imbalance better than 1°
does not yield any improvement in the sideband suppression. For
optimum sideband suppression, an iterative adjustment
between phase and amplitude is required.
The sideband suppression nulling can be performed either through
adjusting the gain for each channel or through the modification
of the phase and gain of the digital data coming from the digital
signal processor.
Rev. 0 | Page 13 of 24
Page 14
ADL5372
APPLICATIONS INFORMATION
DAC MODULATOR INTERFACING
The ADL5372 is designed to interface with minimal components
to members of the Analog Devices family of DACs. These DACs
feature an output current swing from 0 to 20 mA, and the
interface described in this section can be used with any DAC
that has a similar output.
Driving the ADL5372 with a TxDAC®
An example of the interface using the AD9779 TxDAC is shown
Figure 29. The baseband inputs of the ADL5372 require a dc
in
bias of 500 mV. The average output current on each of the
outputs of the
AD9779 is 10 mA. Therefore, a single 50 Ω
resistor to ground from each of the DAC outputs results in an
average current of 10 mA flowing through each of the resistors,
thus producing the desired 500 mV dc bias for the inputs to the
ADL5372.
AD9779F-MOD
OUT1_P
OUT1_N
OUT2_N
OUT2_P
Figure 29. Interface Between the
Ground to Establish the 500 mV DC Bias for the ADL5372 Baseband Inputs
93
RBIP
50Ω
RBIN
50Ω
92
84
RBQN
50Ω
RBQP
50Ω
83
19
IBBP
20
IBBN
23
QBBN
24
QBBP
06511-029
AD9779 and ADL5372 with 50 Ω Resistors to
The AD9779 output currents have a swing that ranges from 0 to
20 mA. With the 50 Ω resistors in place, the ac voltage swing
going into the ADL5372 baseband inputs ranges from 0 V to 1 V.
A full-scale sine wave out of the
AD9779 can be described as a
1 V p-p single-ended (or 2 V p-p differential) sine wave with a
500 mV dc bias.
LIMITING THE AC SWING
There are situations in which it is desirable to reduce the ac
voltage swing for a given DAC output current. This can be
achieved through the addition of another resistor to the interface.
This resistor is placed in the shunt between each side of the
differential pair, as shown in
reducing the ac swing without changing the dc bias already
established by the 50 Ω resistors.
Figure 30. It has the effect of
AD9779F-MOD
OUT1_P
OUT1_N
OUT2_N
OUT2_P
93
RBIP
50Ω
RBIN
50Ω
92
84
RBQN
50Ω
RBQP
50Ω
83
RSLI
100Ω
RSLQ
100Ω
19
IBBP
20
IBBN
23
QBBN
24
QBBP
Figure 30. AC Voltage Swing Reduction Through the Introduction
of a Shunt Resistor Between Differential Pair
The value of this ac voltage swing limiting resistor is chosen
based on the desired ac voltage swing.
Figure 31 shows the
relationship between the swing-limiting resistor and the peakto-peak ac swing that it produces when 50 Ω bias-setting
resistors are used.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
DIFFERENTIAL SWING (V p-p)
0.4
0.2
0
10100100010000
RL (Ω)
06511-031
Figure 31. Relationship Between the AC Swing-Limiting Resistor and the
Peak-to-Peak Voltage Swing with 50 Ω Bias-Setting Resistors
FILTERING
It is necessary to low-pass filter the DAC outputs to remove
images when driving a modulator. The interface for setting up
the biasing and ac swing that was discussed in the
AC Swing
section lends itself well to the introduction of such a
filter. The filter can be inserted between the dc bias setting
resistors and the ac swing-limiting resistor. Doing so establishes
the input and output impedances for the filter.
Limiting the
06511-030
Rev. 0 | Page 14 of 24
Page 15
ADL5372
–
–
An example is shown in Figure 32 with a third-order, elliptical,
low-pass filter with a 3 dB frequency of 3 MHz. Matching input
and output impedances makes the filter design easier, so the
shunt resistor chosen is 100 Ω, producing an ac swing of
1 V p-p differential.
C1I
C1Q
LPI
2.7nH
1.1nF
LNI
2.7nH
LNQ
2.7nH
1.1nF
LPQ
2.7nH
C2I
C2Q
RSLI
100Ω
RSLQ
100Ω
19
IBBP
20
IBBN
23
QBBN
24
QBBP
AD9779F-MOD
OUT1_P
OUT1_N
OUT2_N
OUT2_P
93
92
84
83
RBIP
50Ω
RBIN
50Ω
RBQN
50Ω
RBQP
50Ω
1.1nF
1.1nF
Figure 32. DAC Modulator Interface with
3 MHz Third-Order, Elliptical Low-Pass Filter
USING THE AD9779 AUXILIARY DAC FOR CARRIER
FEEDTHROUGH NULLING
The AD9779 features an auxiliary DAC that can be used to
inject small currents into the differential outputs for each main
DAC channel. This feature can be used to produce the small
offset voltages necessary to null out the carrier feedthrough
from the modulator.
to use the auxiliary DACs. This adds four resistors to the
interface.
AUX1_P
AD9779F-MOD
OUT1_P
OUT1_N
AUX1_N
AUX2_N
OUT2_N
OUT2_P
AUX2_P
90
500Ω
93
92
89
500Ω
87
500Ω
84
83
86
500Ω
Figure 33. DAC Modulator Interface with Auxiliary DAC Resistors
Figure 33 shows the interface required
RBIP
50Ω
RBIN
50Ω
RBQN
50Ω
RBQP
50Ω
250Ω
1.1nF
250Ω
250Ω
1.1nF
250Ω
C1I
C1Q
LPI
2.7nH
1.1nF
LNI
2.7nH
LNQ
2.7nH
1.1nF
LPQ
2.7nH
C2I
C2Q
RSLI
100Ω
RSLQ
100Ω
19
IBBP
20
IBBN
23
QBBN
24
QBBP
06511-032
06511-033
GSM OPERATION
Figure 34 shows the GSM EVM, spectral mask, and noise vs. the
output power for the ADL5372 at 1960 MHz. For a given LO
amplitude, the performance is independent of output power.
4.0
3.5
3.0
2.5
2.0
1.5
PEAK AND RMS EVM (%)
1.0
0.5
0
–6–4–20246
OUTPUT POWER (dBm)
250kHz
PEAK EVM
400kHz
600kHz
1.2MHz
RMS EVM
6 MHz NOISE FLOOR
Figure 34. GSM EVM and Spectral Performance vs. Channel Power at
1960 MHz vs. Output Power; LO Power = 0 dBm
Figure 35 shows the GSM EVM and noise performance vs. the
LO amplitude at 1960 MHz with an output power of 5 dBm.
Increasing the LO drive level improves the noise performance
but degrades EVM performance.
4.0
3.5
3.0
2.5
2.0
1.5
RMS EVM
PEAK AND RMS EVM (%)
1.0
0.5
0
–6–4–20246
LO DRIVE (dBm)
PEAK EVM
6MHz NOISE F LOOR
Figure 35. GSM EVM and 6 MHz Noise Floor vs. LO Power at 1960 MHz;
Output Power = 5 dBm
Figure 35 illustrates that an LO amplitude of 3 dBm provides
the ideal operating point for noise and EVM for a GSM signal
at 1960 MHz.
30
–40
–50
–60
–70
–80
–90
–100
–110
80
–85
–90
–95
–100
–105
–110
–115
–120
SPECTRAL MASK (d Bc/30kHz)
250kHz, 400kHz, 600kHz AND 1200kHz
6MHz OFFS ET NOIS E FLOOR (dBc/100kHz)
6MHz OFF SET NOI SE FLO OR (dBc/100 kHz)
06511-026
06511-027
Rev. 0 | Page 15 of 24
Page 16
ADL5372
–
–
–
–
–
–
WCDMA OPERATION
The ADL5372 is suitable for operation in a WCDMA
environment, providing better than 72.5 dB of adjacent channel
power ratio (ACPR) at an output power of −10 dBm, with a
20 MHz noise floor of −157 dBm/Hz.
Figure 36 and Figure 37
show the ACPR and 20 MHz offset noise floor of the ADL5372
vs. the output power at LO frequencies of 1966 MHz and
2140 MHz, respectively.
70
–72
–74
–76
–78
POWER RATI OS (dB)
–80
ADJACENT AND ALTERNATE CHANNEL
–82
–14–13–12–11–10–9–8–7
ALTERNATE CPR
ADJACENT CPR
20MHz NOISE F LOOR
P
(dBm)
OUT
Figure 36. WCDMA Adjacent and Alternate Channel Power ratios and
20 MHz Offset Noise Floor vs. Output Power at 1966 MHz; LO Power = 0 dBm
70
–72
–74
–76
–78
POWE R RATIO S (dB)
–80
ADJACENT AND ALTERNATE CHANNEL
–82
–14–13–12–11–10–9–8–7
ADJACENT CPR
20MHz NOISE F LOOR
P
(dBm)
OUT
ALTERNATE CPR
Figure 37. WCDMA Adjacent and Alternate Channel Power and 20 MHz
Offset Noise Floor vs. Output Power at 2140 MHz; LO Power = 0 dBm
155.5
–156.0
–156.5
–157.0
–157.5
–158.0
–158.5
155.5
–156.0
–156.5
–157.0
–157.5
–158.0
–158.5
WiMAX OPERATION
Figure 38 demonstrates the ACPR vs. the output power for the
ADL5372 at 2350 MHz. The following test conditions were
applied: a 10 MHz wide 64-QAM OFDM signal with 256
subcarriers, and a raised cosine filter with an α = 0.2.
58
–60
–62
–64
–66
ACPR (dB)
–68
–70
–72
–16–14–12–10–8–6–4–2
ACPR
70MHz OFFSET NOISE FLOOR
OUTPUT PO WER (dBm)
153
–154
–155
–156
–157
–158
–159
–160
70MHz OFFSET NOISE FLOOR (dBm/Hz)
06511-046
Figure 38. WiMAX ACPR and Noise Floor vs. Output Power at 2350 MHz;
LO Power = 0 dBm
LO GENERATION USING PLLS
Analog Devices has a line of PLLs that can be used for generating
20MHz OFFSET NOIS E FLOO R (dBm/Hz)
the LO signal.
frequency and phase noise performance.
The ADF4360 comes as a family of chips, with nine operating
frequency ranges. One is chosen, depending on the local
20MHz OFFSET NOISE FLOOR (dBm/Hz)
oscillator frequency required. While the use of the integrated
synthesizer may come at the expense of slightly degraded noise
performance from the ADL5372, it can be a cheaper alternative
06511-035
to a separate PLL and VCO solution.
available.
Table 5.
Part Output Frequency Range (MHz)
ADF4360-0 2400 to 2725
ADF4360-1 2050 to 2450
ADF4360-2 1850 to 2150
ADF4360-3 1600 to 1950
ADF4360-4 1450 to 1750
ADF4360-5 1200 to 1400
ADF4360-6 1050 to 1250
ADF4360-7 350 to 1800
ADF4360-8 65 to 400
Table 4 lists the PLLs together with their maximum
The AD9779 recommended in the previous sections of this data
sheet is by no means the only DAC that can be used to drive the
ADL5372. There are other appropriate DACs, depending on the
level of performance required.
offered by Analog Devices.
All DACs listed have nominal bias levels of 0.5 V and use the
same simple DAC modulator interface that is shown in
Figure 32.
MODULATOR/DEMODULATOR OPTIONS
Tabl e 7 lists other Analog Devices modulators and demodulators.
Table 7. Modulator/Demodulator Options
Modulator/
Part No.
AD8345 Modulator 140 to 1000
AD8346 Modulator 800 to 2500
AD8349 Modulator 700 to 2700
ADL5390 Modulator 20 to 2400 External quadrature
ADL5385 Modulator 50 to 2200
ADL5370 Modulator 300 to 1000
ADL5371 Modulator 500 to 1500
ADL5373 Modulator 2300 to 3000
ADL5374 Modulator 3000 to 4000
AD8347 Demodulator 800 to 2700
AD8348 Demodulator 50 to 1000
AD8340
AD8341
Demodulator
Vector
modulator
Vector
modulator
Frequency
Range (MHz)
700 to 1000
1500 to 2400
Comments
Rev. 0 | Page 17 of 24
Page 18
ADL5372
EVALUATION BOARD
Populated RoHS-compliant evaluation boards are available for
evaluation of the ADL5372. The ADL5372 package has an
exposed paddle on the underside. This exposed paddle must
be soldered to the board (see the
section). The evaluation board is designed without any
components on the underside so heat can be applied to the
underside for easy removal and replacement of the ADL5372.
QBBPQBBNIBBNIBBP
RFNQ
VPOS
COM1
COM1
VPS1
VPS1
VPS1
VPS1
C12
0.1µF
RFPQ
0Ω
CFPQ
OPEN
1
2
3
4
5
6
CFNQ
0Ω
OPEN
RTQ
OPEN
QBBP
QBBN
2423222120
F-MOD
EXPOSED PADDLE
789
OPEN
COM4
Z1
Power Supply and Grounding
RFNI0ΩRFPI
CFNI
COM4
IBBN
101112
RTI
OPEN
IBBP
19
0Ω
CFPI
OPEN
18
17
16
15
14
13
VPS5
VPS4
VPS3
VPS2
VPS2
VOUT
COUT
100pF
C13
0.1µF
C16
0.1µF
C15
0.1µF
C14
0.1µF
L12
0Ω
L11
0Ω
OPEN
C11
VOUT
06511-037
Figure 40. Evaluation Board Layout, Top Layer
VPOS
LOIP
LOIN
COM2
COM3
CLON
100pF
COM3
06511-036
GND
CLOP
100pF
LO
COM2
Figure 39. ADL5372 Evaluation Board Schematic
Table 8. Evaluation Board Configuration Options
Component Description Default Condition
VPOS, GND Power Supply and Ground Clip Leads. Not applicable
RFPI, RFNI, RFPQ, RFNQ, CFPI,
CFNI, CFPQ, CFNQ, RTQ, RTI
Baseband Input Filters. These components can be used to
implement a low-pass filter for the baseband signals. See
the
Filtering section.
RFNQ, RFPQ, RFNI, RFPI = 0 Ω (0402)
CFNQ, CFPQ, CFNI, CFPI = Open (0402)
RTQ, RTI = Open (0402)
Rev. 0 | Page 18 of 24
Page 19
ADL5372
CHARACTERIZATION SETUP
AEROFLEX IFR 3416
250kHz TO 6GHz SIGNAL G ENERATOR
FREQ 4MHz LEVEL 0dBm
BIAS 0.5V
BIAS 0.5V
AGILENT 34401A
VPOS +5V
AGILENT E3631A
POWER SUPPLY
5.0000.175A
MULTIMETER
0.175 ADC
GAIN 0.7V
GAIN 0.7V
CONNECT TO BACK OF UNIT
I OUTQ OUT
90°
I/AMQ/F M
IQ
RF
OUT
IP
IN
QP
QN
0°
FMOD
R AND S SPECTRUM ANALYZER
FSU 20Hz TO 8GHz
LO
+6dBm
FMOD TEST SETUP
LO
OUTPUT
OUT
GNDVPOS
RF
IN
6V
+
±25V
–
–
+
COM
Figure 41. Characterization Bench Setup
The primary setup used to characterize the ADL5372 is shown
in
Figure 41. This setup was used to evaluate the product as a
single-sideband modulator. The Aeroflex signal generator supplied
the LO and differential I and Q baseband signals to the device
under test, DUT. The typical LO drive was 0 dBm. The I-channel is
driven by a sine wave, and the Q-channel is driven by a cosine
wave. The lower sideband is the single sideband (SSB) output.
6511-038
The majority of characterization for the ADL5372 was performed
using a 1 MHz sine wave signal with a 500 mV common-mode
voltage applied to the baseband signals of the DUT. The baseband
signal path was calibrated to ensure that the V
IOS
and V
QOS
offsets on the baseband inputs were minimized, as close as
possible, to 0 V before connecting to the DUT.
Feedthrough Nulling
section for the definitions of V
See the Carrier
and V
IOS
QOS
.
Rev. 0 | Page 19 of 24
Page 20
ADL5372
TEKTRONI X AFG3252
DUAL FUNCTIO N
ARBITRARY FUNCTI ON GENERATOR
R AND S SMT 06
1MHz
CH1
AMP L 700 mV p- p
PHASE 0°
1MHz
CH2
AMP L 700 mV p- p
PHASE 90°
AGILENT E3631A
POWER SUPPLY
5.0000. 350A
6V
–
VPOS +5V
+
VPOS +5V
AGILENT E3631A
POWER SUPPLY
FREQ 4MHz TO 4GHz
CH1 OUTP UT
CH2 OUTP UT
0°
±25V
–
+
COM
–5V
+5V
90°
IQ
SINGLE TO DIFFERENTIAL
CIRCUIT BOARD
FMOD TEST RACK
Q IN AC
Q IN DCCM
TSEN GND
VPOSB VPOSA
IN1
AGND
VN1VP1
I IN DCCM
I IN AC
IN1
SIGNAL GE NERATOR
LEVEL 0dBm
IP
IN
QP
QN
FMOD
CHAR BD
IP
LO
IN
QP
OUT
QN
GND
VPOS
R AND S FSEA 30
SPECTRUM ANALYZER
RF
OUT
LO
OUTPUT
0.5000. 010A
6V±25V
–
+
VCM = 0.5V
AGILENT 34401A
MULTIMETER
0.200 ADC
–
+
COM
Figure 42. Setup for Baseband Frequency Sweep and Undesired Sideband Nulling
The setup used to evaluate baseband frequency sweep and
undesired sideband nulling of the ADL5372 is shown in
Figure 42.
The interface board has circuitry that converts the single-ended
I input and Q input from the arbitrary function generator to
differential I and Q baseband signals with a dc bias of 500 mV.
RF
IN
100MHz TO 4GHz
+6dBm
06511-039
Undesired sideband nulling was achieved through an iterative
process of adjusting amplitude and phase on the Q-channel. See
Sideband Suppression Optimization section for a detailed
discussion on sideband nulling.
Rev. 0 | Page 20 of 24
Page 21
ADL5372
OUTLINE DIMENSIONS
4.00
PIN 1
INDICATOR
1.00
0.85
0.80
SEATING
PLANE
12° MAX
BSC SQ
TOP
VIEW
0.80 MAX
0.65 TYP
*
COMPLIANT TO JEDEC STANDARDS MO-220-VGGD-2
EXCEPT FOR EXPOSED PAD DIMENSION
0.30
0.23
0.18
3.75
BSC SQ
0.20 REF
0.05 MAX
0.02 NOM
COPLANARITY
0.60 MAX
0.50
BSC
0.50
0.40
0.30
0.08
Figure 43. 24-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
4 mm × 4 mm Body, Very Thin Quad
(CP-24-2)
Dimensions shown in millimeters
0.60 MAX
19
18
EXPOSED
(BOTTOMVIEW)
13
12
PA D
24
6
7
1
2.50 REF
PIN 1
INDICATOR
*
2.45
2.30 SQ
2.15
0.23 MIN
ORDERING GUIDE
Model Temperature Range Package Description Package Option Ordering Quantity