Output frequency range: 2300 MHz to 3000 MHz
Modulation bandwidth: >500 MHz (3 dB)
Output third-order intercept: 26 dBm @ 2500 MHz
1 dB output compression: 13.8 dBm @ 2500 MHz
Noise floor: −157.1 dBm/Hz @ 2500 MHz
Sideband suppression: −57 dBc @ 2500 MHz
Carrier feedthrough: −32 dBm @ 2500 MHz
Single supply: 4.75 V to 5.25 V
24-lead LFCSP
APPLICATIONS
WiMAX/broadband wireless access systems
Satellite modems
GENERAL DESCRIPTION
The ADL5373 supports a frequency of operation from 2300 MHz
to 3000 MHz and is a pin-compatible member of the fixed gain
quadrature modulator (F-MOD) family designed for use from
300 MHz to 4000 MHz. The ADL5373 provides excellent phase
accuracy and amplitude balance enabling high performance
intermediate frequency or direct radio frequency modulation
for communications systems.
The ADL5373 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
ADL5373
FUNCTIONAL BLOCK DIAGRAM
IBBP
IBBN
LOIP
LOIN
QBBN
QBBP
The ADL5373 accepts two differential baseband inputs that
are mixed with a local oscillator (LO) to generate a singleended output.
The ADL5373 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
06664-001
Rev. A
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.
Changes to Features and General Description ............................. 1
Changes to Table 1............................................................................ 3
Changes to Table 2............................................................................ 5
Changes to Figure 3, Figure 4, and Figure 6 to Figure 8.............. 7
Changes to Figure 9 to Figure 14.................................................... 8
Changes to Figure 15 to Figure 20.................................................. 9
Changes to Figure 21 to Figure 23................................................ 10
Changes to Optimization Section and Figure 27 ....................... 13
Changes to Figure 35...................................................................... 15
Changes to WiMAX Operation Section and Figure 36............. 16
Changes to Evaluation Board Section.......................................... 17
Changes to Characterization Setup Section................................ 18
6/07—Revision 0: Initial Version
Rev. A | Page 2 of 20
Page 3
ADL5373
SPECIFICATIONS
VS = 5 V, TA = 25°C, LO = 0 dBm1, 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 2300 MHz
High frequency 3000 MHz
LO = 2300 MHz
Output Power VIQ = 1.4 V p-p differential 4.2 dBm
Output P1dB 11.0 dBm
Carrier Feedthrough −35 dBm
Sideband Suppression −57 dBc
Quadrature Error <0.2 Degrees
I/Q Amplitude Balance 0.06 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
WiMAX 802.16e
LO = 2500 MHz
Output Power VIQ = 1.4 V p-p differential 7.1 dBm
Output P1dB 13.8 dBm
Carrier Feedthrough −32 dBm
Sideband Suppression −57 dBc
Quadrature Error 0.3 Degrees
I/Q Amplitude Balance 0.06 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 802.16e
LO = 2700 MHz
Output Power VIQ = 1.4 V p-p differential 7.7 dBm
Output P1dB 13.8 dBm
Carrier Feedthrough −33 dBm
Sideband Suppression −54 dBc
Quadrature Error <0.2 Degrees
I/Q Amplitude Balance 0.07 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
WiMAX 802.16e
LO INPUTS
LO Drive Level
1
Input Return Loss See Figure 9 for a plot of return loss vs. frequency −6 dB
LO = 2500 MHz, baseband input = 700 mV p-p sine wave on
500 mV dc
0.1 dB 70 MHz
1 dB 350 MHz
POWER SUPPLIES Pin VPS1 and Pin VPS2
Voltage 4.75 5.25 V
Supply Current 174 mA
1
Driven through Johanson Technology balun (Model 2450BL15B050)
2
See V-to-I Converter section for architecture information.
45 μA
Rev. A | Page 4 of 20
Page 5
ADL5373
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter Rating
Supply Voltage VPSx 5.5 V
IBBP, IBBN, QBBP, and QBBN 0 V to 2 V
LOIP and LOIN 13 dBm
Internal Power Dissipation 1119 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. A | Page 5 of 20
Page 6
ADL5373
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
ADL5373
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
06664-002
Figure 2. Pin Configuration
Table 3. Pin Function Descriptions
Pin No. Mnemonic Description
1, 2, 7, 10 to 12, 21, 22 COM1 to COM4 Input Common Pins. Connect to ground plane via a low impedance path.
3 to 6, 14 to 18 VPS1 to VPS5
Positive Supply Voltage Pins. All pins should be connected to the same supply (V
ensure 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
13 VOUT
50 Ω Differential Local Oscillator Input. Internally dc-biased. Pins must be ac-coupled.
See
Figure 8 for LO input impedance.
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 the ground plane via a low impedance path.
). To
S
Rev. A | Page 6 of 20
Page 7
ADL5373
TYPICAL PERFORMANCE CHARACTERISTICS
VS = 5 V, TA = 25°C, LO = 0 dBm, 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
10
9
TA = –40°C
8
7
6
5
4
3
SSB OUTPUT POWER (dBm)
2
1
0
23003000
240025002600270028002900
Figure 3. Single Sideband (SSB) Output Power (P
LO Frequency (f
) = 1 MHz, unless otherwise noted.
BB
TA = +25°C
TA = +85°C
LO FREQUENCY (MHz)
) vs.
) and Temperature
LO
OUT
17
16
TA = –40°C
15
14
13
12
11
10
9
1dB OUTPUT COMPRESSI ON (dBm)
8
06664-003
7
23003000
240025002600270028002900
TA = +25°C
TA = +85°C
LO FREQUENCY (MHz)
06664-006
Figure 6. SSB Output P1dB Compression Point (OP1dB) vs.
f
and Temperature
LO
10
9
8
7
VS = 5.25V
6
5
4
3
SSB OUTPUT POWER (dBm)
2
1
0
23003000
Figure 4. Single Sideband (SSB) Output Power (P
5
0
VS = 5.0V
VS = 4.75V
240025002600270028002900
LO FREQUENCY (MHz)
f
and Supply
LO
OUT
) vs.
17
16
15
14
13
12
11
10
9
1dB OUTPUT COMPRESSI ON (dBm)
8
06664-004
7
23003000
240025002600270028002900
VS = 5.0V
LO FREQUENCY (MHz)
VS = 5.25V
VS = 4.75V
06664-007
Figure 7. SSB Output P1dB Compression Point (OP1dB) vs.
f
and Supply
LO
90
120
2300MHz
150
3000MHz
2300MHz
60
30
0180
OUTPUT PO WER VARIANCE (d B)
–5
1101001000
BASEBAND FREQUENCY (M Hz)
Figure 5. I and Q Input Bandwidth Normalized to
Gain @ 1 MHz (f
= 2500 MHz)
LO
06664-005
Rev. A | Page 7 of 20
300
330
06664-008
210
240
3000MHz
S11 OF LO
S22 OF OUTPUT
270
Figure 8. Smith Chart of LOIP (LOIN AC-Coupled to Ground) S11 and
VOUT S22 (f
from 2300 MHz to 3000 MHz)
LO
Page 8
ADL5373
–
0
–5
–10
–15
RETURN LOSS (d B)
–20
–25
23002400250026002700280029003000
LO FREQ UENCY (MHz)
Figure 9. Return Loss (S11) of LOIP with LOIN AC-Coupled to Ground vs. f
0
–10
–20
–30
–40
–50
TA = –40°C
TA = +25°C
TA = +85°C
0
–10
–20
–30
–40
–50
–60
SIDEBAND SUPPRESSION (dBc)
–70
06664-009
–80
TA = +25°C
23003000
240025002600270028002900
LO
Figure 12. Sideband Suppression vs. f
TA = –40°C
LO FREQUENCY (MHz)
TA = +85°C
and Temperature;
LO
06664-012
Multiple Devices Shown
0
–10
–20
–30
–40
–50
TA = +85°C
TA = –40°C
–60
CARRIER FEEDTHRO UGH (dBm)
–70
–80
23003000
240025002600270028002900
LO FREQUENCY (MHz)
Figure 10. Carrier Feedthrough vs. f
Multiple Devices Shown
0
–10
–20
–30
–40
–50
–60
CARRIER FEEDTHROUG H (dBm)
–70
–80
23003000
TA = +85°C
240025002600270028002900
LO FREQUENCY (MHz)
Figure 11. Carrier Feedthrough vs. f
Multiple Devices Shown
and Temperature;
LO
TA = –40°C
TA = +25°C
and Temperature after Nulling at 25°C;
LO
–60
SIDEBAND SUPPRESSION (dBc)
–70
06664-010
Figure 13. Sideband Suppression vs. f
TA = +25°C
–80
23003000
240025002600270028002900
LO FREQUENCY (MHz)
and Temperature afte r Nulli ng at 25°C;
LO
06664-013
Multiple Devices Shown
20
–30
–40
–50
–60
SIDEBAND SUPPRESSI ON
–70
DISTORTI ON, CARRIER FE EDTHROUGH,
06664-011
SECOND-ORDER DISTORTI ON, THIRD-O RDER
–80
CARRIER
FEEDTHROUG H (dBm)
SSB OUTPUT
POWER (d Bm)
SECOND-ORDER
DISTORTION (dBc)
0.23.4
0.61.01.41.82. 22. 63. 0
BASEBAND INPUT VO LTAGE ( V p-p)
THIRD-ORDER
DISTORTION (dBc)
SIDEBAND
SUPPRESSION (dBc)
15
10
5
0
–5
–10
–15
SSB OUTPUT POWER (dBm)
06664-014
Figure 14. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
vs. Baseband Differential Input Level
OUT
= 2300 MHz)
(f
LO
Rev. A | Page 8 of 20
Page 9
ADL5373
–
–
–
–
20
–30
–40
–50
CARRIER
FEEDTHROUG H (dBm)
SSB OUTPUT P OWER (d Bm)
SIDEBAND
SUPPRESSION (dBc)
15
10
5
0
30
TA = –40°C
25
TA = +25°C
20
15
TA = +85°C
–60
SIDEBAND SUPPRESSI ON
DISTORTI ON, CARRIER FE EDTHROUGH,
SECOND-ORDER DISTORTI ON, THIRD-O RDER
THIRD-ORDER
–70
DISTORTION (dBc)
–80
0.23.4
0.61.01.41.82.22.63.0
BASEBAND INPUT VOLTAGE (V p-p)
SECOND-ORDER
DISTORTION (dBc)
Figure 15. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
20
–30
THIRD-ORDER
DISTORTION
–40
T
= +85°C
A
–50
–60
SECOND-ORDER
THIRD-ORDER DIS TORTION (dBc)
–70
SECOND-ORDER DIS TORTIO N AND
DISTORTI ON
T
= +85°C
A
–80
23003000
240025002600270028002900
Figure 16. Second- and Third-Order Distortion vs. f
vs. Baseband Differential Input Level
OUT
(f
= 2700 MHz)
LO
THIRD-ORDER
DISTORTION
T
= –40°C
A
SECOND-ORDER
DISTORTI ON
T
= +25°C
A
LO FREQUE NCY (MHz)
THIRD-ORDER
DISTORTI ON
T
= +25°C
A
SECOND-ORDER
DISTORTION
T
= –40°C
A
and Temperature
LO
(Baseband I/Q Amplitude = 1.4 V p-p Differential)
–5
–10
–15
10
SSB OUTPUT POWER (dBm)
06664-015
06664-016
5
OUTPUT THIRD-ORDER INTE RCEPT (dBm)
0
23003000
240025002600270028002900
LO FREQUENCY (MHz)
Figure 18. OIP3 vs. f
80
70
TA = +25°C
60
50
40
30
20
10
OUTPUT SECO ND-ORDER INTERCEPT (dBm)
0
23003000
TA = +85°C
240025002600270028002900
Figure 19. OIP2 vs. f
and Temperature
LO
TA = –40°C
LO FREQUENCY (MHz)
and Temperature
LO
06664-018
06664-019
20
CARRIER
–30
–40
SUPPRESSION (dBc)
–50
–60
–70
SECOND-ORDER DIS TORTIO N, CARRIER
FEEDTHROUG H, SIDEBAND SUPPRESSION
–80
1M100M
FEEDTHROUG H (dBm)
SIDEBAND
SECOND-ORDER
DISTORTION (dBc)
BASEBAND FREQUENCY (Hz)
10M
Figure 17. Second-Order Distortion, Carrier Feedthrough, and Sideband
Suppression vs. f
(fLO = 2500 MHz)
BB
SECOND-ORDER DISTORTION, THIRD-ORDER
06664-017
Rev. A | Page 9 of 20
20
–30
–40
–50
SIDEBAND SUPPRESSION
–60
DISTORTI ON, CARRIER FEEDT HROUGH,
–70
–66
CARRIER
FEEDTHROUGH (dBm)
–5–4–3–2–1012345
SSB OUTPUT POWER (dBm)
THIRD-ORDER
DISTORTION (dBc)
SIDEBAND SUPPRESSION (dBc)
SECOND-ORDER
DISTORTION (dBc)
LO AMPLIT UDE (dBm)
5
4
3
2
1
0
Figure 20. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
vs. LO Amplitude (fLO = 2300 MHz)
OUT
SSB OUTPUT PO WER (dBm)
06664-020
Page 10
ADL5373
–
20
SSB OUTPUT POWER (dBm)
–30
THIRD-ORDER
–40
–50
SIDEBAND SUPPRESSION
–60
DISTORTI ON, CARRIER FEEDT HROUGH,
SECOND-ORDER DISTORTION, THIRD-ORDER
–70
–66
DISTORTION (dBc)
–5–4–3–2–1012345
LO AMPLIT UDE (dBm)
CARRIER
FEEDTHROUGH (dBm)
SIDEBAND SUPPRESSIO N (dBc)
SECOND-ORDER
DISTORTION (dBc)
Figure 21. Second- and Third-Order Distortion, Carrier Feedthrough,
Sideband Suppression, and SSB P
0.20
0.19
VS = 5.25V
0.18
VS = 5.0V
0.17
VS = 4.75V
0.16
0.15
0.14
0.13
SUPPLY CURRENT (A)
0.12
0.11
0.10
–4085
vs. LO Amplitude (fLO = 2700 MHz)
OUT
25
TEMPERATURE ( °C)
Figure 22. Power Supply Current vs. Temperature
25
8
20
7
15
6
QUANTITY
10
5
SSB OUTPUT PO WER (dBm)
4
3
06664-021
5
0
–158.1
–157.9
–157.7
–157.5
–157.3
–157.1
NOISE AT 20M Hz OFFS ET (dBm/Hz )
–156.9
Figure 23. 20 MHz Offset Noise Floor Distribution at f
f
= 2500MHz
LO
–156.7
–156.5
–156.3
–156.1
–155.9
–155.7
06664-023
= 2500 MHz
LO
(I/Q Amplitude = 0 mV p-p with 500 mV dc Bias)
06664-022
Rev. A | Page 10 of 20
Page 11
ADL5373
THEORY OF OPERATION
CIRCUIT DESCRIPTION
Overview
The ADL5373 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. For optimal performance, the LO should be
driven differentially. 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
VOUT
6664-024
V-to-I Converter
The differential baseband inputs (QBBP, QBBN, IBBN, and
IBBP) consist of the bases of the 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 ADL5373 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); therefore, 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. A | Page 11 of 20
Page 12
ADL5373
BASIC CONNECTIONS
Figure 25 shows the basic connections for the ADL5373.
QBBPQBBN IBBNIBBP
C16
VPOS
COM1
COM1
VPS1
VPS1
VPS1
VPS1
C12
0.1µF
1
2
3
4
5
6
GND
RLOP
OPEN
CLOP
100pF
QBBP
COM4
QBBN
2423222120
Z1
F-MOD
EXPOSED PADDLE
789
LOIP
LOIN
COM2
CLON
100pF
34
2
5
NC
6
1
T1
JOHANSON
TECHNOLOG Y
2450BL15B050
COM4
IBBN
101112
COM2
COM3
RLON
OPEN
LO
IBBP
COM3
19
VPS5
18
VPS4
17
VPS3
16
VPS2
15
VPS2
14
VOUT
13
COUT
100pF
C13
0.1µF
0.1µF
C15
0.1µF
C14
0.1µF
C11
OPEN
VPOS
VOUT
Figure 25. Basic Connections for the ADL5373
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. Locate these capacitors as close as possible
to the device. The power supply can range between 4.75 V and
5.25 V.
06664-025
The COM1, COM2, COM3, and COM4 pins should be tied to
the same ground plane through low impedance paths. Solder the
exposed paddle on the underside of the package 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.
Application Note AN-772 describes the thermal and electrical
grounding of the LFCSP in detail.
BASEBAND INPUTS
The baseband inputs QBBP, QBBN, IBBP, and IBBN must be
driven from a differential source. Bias the nominal drive level of
1.4 V p-p differential (700 mV p-p on each pin) to a commonmode level of 500 mV dc.
The dc common-mode bias level for the baseband inputs can
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
ADL5373 input range and on the top end by the output compliance
range on most DACs from Analog Devices.
LO INPUT
The LO input should be driven differentially. The recommended
balun for the ADL5373 is the Johanson Technology model
2450BL15B050. The LO pins should be ac-coupled to the balun.
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. If the LO source cannot provide the 0 dBm level,
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
Figure 20 and Figure 21.
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
performance). The internal balun provides a low dc path to
ground. In most situations, the VOUT pin should be ac-coupled
to the load.
Figure 8 for S22
Rev. A | Page 12 of 20
Page 13
ADL5373
–
–
OPTIMIZATION
The carrier feedthrough and sideband suppression performance
of the ADL5373 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 ADL5373 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 2500 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
IOPP
VP – VN OFFSET (µV)
IOPN
) and (V
QOPP
IOPP
− V
− V
= 0 V
is applied to the I-channel inputs,
/2, and
IOS
/2, such that
IOS
QOPN
IOPN
)
)
06664-026
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 ±100 MHz on either side of a null at 2600 MHz.
Figure 27. Carrier Feedthrough vs. Frequency After Nulling at 2600 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)
06664-028
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. A | Page 13 of 20
Page 14
ADL5373
APPLICATIONS INFORMATION
DAC MODULATOR INTERFACING
The ADL5373 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 mA to 20 mA, and the
interface described in this section can be used with any DAC
that has a similar output.
Driving the ADL5373 with a TxDAC®
An example of the interface using the AD9779 TxDAC is shown
Figure 29. The baseband inputs of the ADL5373 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 ADL5373.
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 ADL5373 Baseband Inputs
93
RBIP
50Ω
RBIN
50Ω
92
84
RBQN
50Ω
RBQP
50Ω
83
19
IBBP
20
IBBN
23
QBBN
24
QBBP
06664-029
AD9779 and ADL5373 with 50 Ω Resistors to
The AD9779 output currents have a swing that ranges from
0 mA to 20 mA. With the 50 Ω resistors in place, the ac voltage
swing going into the ADL5373 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 a 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)
06664-031
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 described 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, which establishes the input
and output impedances for the filter.
Limiting the
06664-030
Rev. A | Page 14 of 20
Page 15
ADL5373
–
–
An example is shown in Figure 32 with a third-order, Bessel
low-pass filter with a 3 dB frequency of 10 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. The frequency response of this filter is
shown in
AD9779F-MOD
OUT1_P
OUT1_N
OUT2_N
OUT2_P
Figure 33.
LPI
C1I
C1Q
771.1nH
350.1pF
C2I
LNI
771.1nH
LNQ
771.1nH
350.1pF
C2Q
LPQ
771.1nH
93
RBIP
50Ω
53.62nF
RBIN
50Ω
92
84
RBQN
50Ω
53.62nF
RBQP
50Ω
83
Figure 32. DAC Modulator Interface with
10 MHz Third-Order Bessel Filter
RSLI
100Ω
RSLQ
100Ω
19
IBBP
20
IBBN
23
QBBN
24
QBBP
0
–10
–20
GROUP DELAY
–30
MAGNITUDE (dB)
–40
–50
–60
110100
FREQUENCY (MHz)
MAGNITUDE
Figure 33. Frequency Response for DAC Modulator Interface
with 10 MHz Third-Order Bessel Filter
36
30
24
18
12
GROUP DELAY (ns)
6
0
06664-033
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, which adds four resistors to the
interface.
Figure 34 shows the interface required
AUX1_P
AD9779F-MOD
OUT1_P
OUT1_N
AUX1_N
AUX2_N
OUT2_N
OUT2_P
AUX2_P
06664-032
WiMAX OPERATION
Figure 35 shows the first and second adjacent channel power
ratios (10 MHz offset and 20 MHz offset), and the 30 MHz
offset noise floor vs. output power for a 10 MHz 1024-OFDMA
waveform at 2600 MHz.
ADJACENT AND ALTERNATE
CHANNEL POWER RAT IOS (d B)
Figure 35. Adjacent and Alternate Channel Power Ratios and 30 MHz Offset
Noise Floor vs. Channel Power for a 10 MHz 1024-OFDMA Waveform at
Figure 35 illustrates that optimal performance is achieved when
the output power from the modulator is −10 dBm or greater.
The noise floor rises with increasing output power, but at less
than half the rate at which ACPR degrades. Therefore, operating
at powers greater than −10 dBm can improve the signal-tonoise ratio.
90
500Ω
93
92
500Ω
500Ω
89
500Ω
87
84
RBQN
RBQP
83
86
RBIP
50Ω
RBIN
50Ω
50Ω
50Ω
250Ω
53.62nF
C1I
250Ω
250Ω
53.62nF
C1Q
250Ω
LPI
771.1nH
350.1pF
LNI
771.1nH
LNQ
771.1nH
350.1pF
C2Q
LPQ
771.1nH
C2I
RSLI
100Ω
RSLQ
100Ω
19
IBBP
20
IBBN
23
QBBN
24
QBBP
Figure 34. DAC Modulator Interface with Auxiliary DAC Resistors
62
–64
–66
–68
–70
–72
–74
–76
–78
ADJACENT CHANNEL
POWER RATIO
30MHz OFF SET
NOISE FLOOR
ALTERNATE CHANNEL
POWER RATI O
–18–16–14–12–10–8–6–4–2
OUTPUT PO WER (dBm)
2600 MHz; LO Power = 0 dBm
151
–152
–153
–154
–155
–156
–157
–158
–159
06664-034
30MHz OFFSET NOISE FLOOR (dBm/Hz)
06664-035
Rev. A | Page 15 of 20
Page 16
ADL5373
Figure 36 shows the error-vector magnitude (EVM) vs. output
power for a 10 MHz, 1024-OFDMA waveform at 2600 MHz.
2.0
1.8
1.6
1.4
1.2
1.0
0.8
0.6
0.4
ERROR VECTOR MAGNITUDE (%)
0.2
0
–19–17–15–13–11–9–7–5–3
OUTPUT PO WER (dBm)
Figure 36. Error Vector Magnitude (EVM) vs. Output Power for 10 MHz,
1024-OFDMA Waveform at 2600 MHz; LO Power = 0 dBm
6664-036
LO GENERATION USING PLLs
Analog Devices has a line of PLLs that can be used for generating
the LO signal.
frequency and phase noise performance.
Table 4 lists the PLLs together with their maximum
TRANSMIT DAC OPTIONS
The AD9779 recommended in the previous sections of this data
sheet is not the only DAC that can be used to drive the ADL5373.
There are other appropriate DACs, depending on the level of
performance required.
Analog Devices.
The ADF4360 comes as a family of chips, with nine operating
frequency ranges. A device is chosen depending on the local
oscillator frequency required. Although the use of the integrated
synthesizer may come at the expense of slightly degraded noise
performance from the ADL5373, it can be a cheaper alternative
to a separate PLL and VCO solution.
Tabl e 5 shows the options
available.
Table 5.
ADF4360 Family Operating Frequencies
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
MODULATOR/DEMODULATOR OPTIONS
Tabl e 7 lists other Analog Devices modulators and demodulators.
Table 7. Modulator/Demodulator Options
Modulator/
Part No.
Demodulator
AD8345Modulator 140 to 1000
AD8346Modulator 800 to 2500
AD8349Modulator 700 to 2700
ADL5390Modulator 20 to 2400
ADL5385Modulator 50 to 2200
ADL5370Modulator 300 to 1000
ADL5371Modulator 500 to 1500
ADL5372Modulator 1500 to 2500
ADL5374Modulator 3000 to 4000
AD8347Demodulator 800 to 2700
AD8348Demodulator 50 to 1000
AD8340Vector modulator 700 to 1000
AD8341Vector modulator 1500 to 2400
Frequency
Range (MHz)
Comments
External
quadrature
Rev. A | Page 16 of 20
Page 17
ADL5373
EVALUATION BOARD
A populated RoHS-compliant evaluation board is available for
evaluation of the ADL5373. The ADL5373 package has an
exposed paddle on the underside. This exposed paddle must
be soldered to the board (see the
Power Supply and Grounding
section). The evaluation board has no components on the
underside so heat can be applied to the underside for easy
removal and replacement of the ADL5373.
QBBPQBBNIBBNIBBP
RFNQ
VPOS
COM1
COM1
VPS1
VPS1
VPS1
VPS1
C12
0.1µF
RFPQ
CFPQ
OPEN
0Ω
RTQ
OPEN
1
2
3
4
5
6
CFNQ
0Ω
OPEN
QBBP
COM4
QBBN
2423222120
F-MOD
EXPOSED PADDLE
789
OPEN
Z1
CFNI
COM4
IBBN
101112
RFNI0ΩRFPI
0Ω
RTI
CFPI
OPEN
OPEN
IBBP
19
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
C11
OPEN
VOUT
VPOS
Figure 38. Evaluation Board Layout, Top Layer
Yup in g Toh
06664-038
LOIP
LOIN
GND
RLOP
OPEN
CLOP
100pF
COM2
NC
JOHANSON
TECHNOLOGY
2450BL15B050
COM2
COM3
COM3
CLON
100pF
RLON
OPEN
34
2
5
6
1
LO
T1
6664-037
Figure 37. ADL5373 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. A | Page 17 of 20
Page 18
ADL5373
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
6V
+
MULTIMETER
0.175 ADC
±25V
–
+
COM
GAIN 0.7V
GAIN 0.7V
CONNECT TO BACK OF UNIT
I/AMQ/F M
I OUTQ OUT
90°
–
IQ
Figure 39. Characterization Bench Setup
The primary setup used to characterize the ADL5373 is shown
Figure 39. This setup was used to evaluate the product as a
in
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.
RF
OUT
0°
F-MOD
IP
IN
QP
QN
The majority of characterization for the ADL5373 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
offsets on the baseband inputs were minimized, as close as
possible, to 0 V before connecting to the DUT.
R AND S SPECTRUM ANALYZER
FSU 20Hz TO 8GHz
LO
+6dBm
F-MOD TEST SETUP
LO
OUTPUT
OUT
GNDVPOS
RF
IN
6664-039
IOS
and V
QOS
Rev. A | Page 18 of 20
Page 19
ADL5373
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-T O-DIFF ERENTIAL
CIRCUIT BOARD
F-MOD TES T 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
F-MOD
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 40. Setup for Baseband Frequency Sweep and Undesired Sideband Nulling
The setup used to evaluate baseband frequency sweep and
undesired sideband nulling of the ADL5373 is shown in
Figure 40.
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
06664-040
Undesired sideband nulling was achieved through an iterative
process of adjusting amplitude and phase on the Q-channel. See
the
Sideband Suppression Optimization section for detailed
information on sideband nulling.
Rev. A | Page 19 of 20
Page 20
ADL5373
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 41. 24-Lead Lead Frame Chip Scale Package [LFCSP_VQ]
4 mm × 4 mm Body, Very Thin Quad
(CP-24-2)
Dimensions shown in millimeters
ORDERING GUIDE
Model Temperature Range Package Description Package Option Ordering Quantity
ADL5373ACPZ-R7
ADL5373ACPZ-WP
ADL5373-EVALZ
1
Z = RoHS Compliant Part.
1
−40°C to +85°C 24-Lead LFCSP_VQ, 7” Tape and Reel CP-24-2 1,500
1
−40°C to +85°C 24-Lead LFCSP_VQ, Waffle Pack CP-24-2 64