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0.8 GHz to 2.5 GHz
Quadrature Modulator
AD8346
FEATURES
High accuracy
1 degree rms quadrature error @ 1.9 GHz
0.2 dB I/Q amplitude balance @ 1.9 GHz
Broad frequency range: 0.8 GHz to 2.5 GHz
Sideband suppression: −46 dBc @ 0.8 GHz
Sideband suppression: −36 dBc @ 1.9 GHz
Modulation bandwidth: dc to 70 MHz
0 dBm output compression level @ 0.8 GHz
Noise floor: −147 dBm/Hz
Single 2.7 V to 5.5 V supply
Quiescent operating current: 45 mA
Standby current: 1 μA
16-lead TSSOP
FUNCTIONAL BLOCK DIAGRAM
IBBP
IBBN
COM1
COM1
LOIN
LOIP
VPS1
ENBL
1
2
3
4
5
6
7
PHASE
SPLITTER
16
15
14
13
12
QBBP
QBBN
COM4
COM4
VPS2
11 VOUT
10 COM3
8
BIAS
9
COM2
Figure 1.
APPLICATIONS
Digital and spread spectrum communication systems
Cellular/PCS/ISM transceivers
Wireless LAN/wireless local loop
QPSK/GMSK/QAM modulators
Single-sideband (SSB) modulators
Frequency synthesizers
Image reject mixer
GENERAL DESCRIPTION
The AD8346 is a silicon RFIC I/Q modulator for use from
0.8 GHz to 2.5 GHz. Its excellent phase accuracy and amplitude
balance allow high performance direct modulation to RF.
The differential LO input is applied to a polyphase network
phase splitter that provides accurate phase quadrature from
0.8 GHz to 2.5 GHz. Buffer amplifiers are inserted between
two sections of the phase splitter to improve the signal-to-
noise ratio. The I and Q outputs of the phase splitter drive the
LO inputs of two Gilbert-cell mixers. Two differential V-to-I
converters connected to the baseband inputs provide the
baseband modulation signals for the mixers. The outputs of
the two mixers are summed together at an amplifier which is
designed to drive a 50 Ω load.
This quadrature modulator can be used as the transmit mod-
ulator in digital systems such as PCS, DCS, GSM, CDMA, and
ISM transceivers. The baseband quadrature inputs are directly
modulated by the LO signal to produce various QPSK and
QAM formats at the RF output.
Additionally, this quadrature modulator can be used with direct
digital synthesizers in hybrid phase-locked loops to generate
signals over a wide frequency range with millihertz resolution.
The AD8346 comes in a 16-lead TSSOP package, measuring
6.5 mm × 5.1 mm × 1.1 mm. It is specified to operate over a
−40°C to +85°C temperature range and a 2.7 V to 5.5 V supply
voltage range. The device is fabricated on Analog Devices’ high
performance 25 GHz bipolar silicon process.
Rev. A
Information furnished by Analog Devices is believed to be accurate and reliable.
However, no responsibility is assumed by Analog Devices for its use, nor for any
infringements of patents or other 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 companies.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
www.analog.com
Tel: 781.329.4700
Fax: 781.461.3113
© 2005 Analog Devices, Inc. All rights reserved.
05335-001
AD8346
AD8346
TABLE OF CONTENTS
Specifications..................................................................................... 3
Absolute Maximum Ratings............................................................ 4
ESD Caution.................................................................................. 4
Pin Configuration and Function Descriptions............................. 5
Equivalent Circuits ........................................................................... 6
Typical Performance Characteristics ............................................. 7
Circuit Description......................................................................... 10
Overview...................................................................................... 10
LO Interface................................................................................. 10
V-to-I Converter......................................................................... 10
Mixers .......................................................................................... 10
Differential-to-Single-Ended Converter ................................. 10
Bias ............................................................................................... 10
Basic Connections...................................................................... 11
LO Drive ...................................................................................... 11
RF Output.................................................................................... 11
Interface to AD9761 T
X
DAC® .................................................. 12
AC-Coupled Interface ............................................................... 13
Evaluation Board ............................................................................ 14
Characterization Setups................................................................. 16
SSB Setup..................................................................................... 16
CDMA Setup............................................................................... 17
Outline Dimensions ....................................................................... 18
Ordering Guide .......................................................................... 18
REVISION HISTORY
6/05—Rev. 0 to Rev. A
Updated Format..................................................................Universal
Changes to Figures 30, 31, 32........................................................ 14
Update Outline Dimensions ......................................................... 18
Changes to Ordering Guide .......................................................... 18
3/99—Revision 0: Initial Version
Rev. A | Page 2 of 20
AD8346
SPECIFICATIONS
V
S
= 5 V; T
A
= 25°C; LO frequency = 1900 MHz; LO level = –10 dBm; BB frequency = 100 kHz; BB inputs are dc-biased to 1.2 V; BB input
level = 1.0 V p-p each pin for 2.0 V p-p differential drive; LO source and RF output load impedances are 50 Ω, dBm units are referenced
to 50 Ω unless otherwise noted.
Table 1.
Parameters
RF OUTPUT
Operating Frequency
Quadrature Phase Error
I/Q Amplitude Balance
Output Power
Output VSWR
Output P1 dB
Carrier Feedthrough
Sideband Suppression
IM3 Suppression
Equivalent Output IP3
Output Noise Floor
RESPONSE TO CDMA IS95 BASEBAND SIGNALS
ACPR (Adjacent Channel Power Ratio)
EVM (Error Vector Magnitude)
Rho (Waveform Quality Factor)
MODULATION INPUT
Input Resistance
Modulation Bandwidth
LO INPUT
LO Drive Level
Input VSWR
ENABLE
ENBL HI Threshold
ENBL LO Threshold
ENBL Turn-On Time
ENBL Turn-Off Time
POWER SUPPLIES
Voltage
Current Active (ENBL HI)
Current Standby (ENBL LO)
Conditions
Min
0.8
See Figure 35 for setup
See Figure 35 for setup
I and Q channels in quadrature
1
0.2
−10
1.25:1
−3
−42
−36
−60
20
−147
−72
2.5
0.9974
12
70
−12
1.9:1
2.0
0.5
Settle to within 0.5 dB of final SSB
output power
Time for supply current to drop below
2 mA
2.7
35
2.5
12
V
V
μs
μs
−6
Typ
Max
2.5
Unit
GHz
Degree rms
dB
dBm
dBm
dBm
dBc
dBc
dBm
dBm/Hz
dBc
%
−13
−6
−35
−25
20 MHz offset from LO
See Figure 35 for setup
See Figure 35 for setup
See Figure 35 for setup
−3 dB
kΩ
MHz
dBm
45
1
5.5
55
20
V
mA
μA
Rev. A | Page 3 of 20
AD8346
ABSOLUTE MAXIMUM RATINGS
Table 2.
Parameter
Supply Voltage VPS1, VPS2
Input Power LOIP, LOIN (relative to 50 Ω)
Min Input Voltage IBBP, IBBN, QBBP, QBBN
Max Input Voltage IBBP, IBBN, QBBP, QBBN
Internal Power Dissipation
θJA
Operating Temperature Range
Storage Temperature Range
Lead Temperature (Soldering 60 sec)
Min Rating
5.5 V
10 dBm
0V
2.5 V
500 mW
125°C/W
−40°C to +85°C
−65°C to +150°C
300°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 condition s 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
ESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000 V readily accumulate on the
human body and test equipment and can discharge without detection. Although this product features
proprietary ESD protection circuitry, permanent damage may occur on devices subjected to high energy
electrostatic discharges. Therefore, proper ESD precautions are recommended to avoid performance
degradation or loss of functionality.
Rev. A | Page 4 of 20
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