1.5 GHz to 2.4 GHz
RF Vector Modulator

AD8341


Rev. 0
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FEATURES
Cartesian amplitude and phase modulation
1.5 GHz to 2.4 GHz frequency range
Continuous magnitude control of −4.5 dB to −34.5 dB
Continuous phase control of 0° to 360°
Output third-order intercept 17.5 dBm
Output 1 dB compression point 8.5 dBm
Output noise floor −150.5 dBm/Hz @ full gain
Adjustable modulation bandwidth up to 230 MHz
Fast output power disable
4.75 V to 5.25 V single-supply voltage

APPLICATIONS
RF PA linearization/RF predistortion
Amplitude and phase modulation
Variable attenuators and phase shifters
CDMA2000, WCDMA, GSM/EDGE linear power amplifiers
Smart antennas

FUNCTIONAL BLOCK DIAGRAM

90°
0°
VPS2QBBMQBBP
RFIP
RFIM
DSOPIBBMIBBP
RFOP
RFOM
04700-001
VPRF
CMOP

Figure 1.

GENERAL DESCRIPTION
The AD8341 vector modulator performs arbitrary amplitude
and phase modulation of an RF signal. Since the RF signal path
is linear, the original modulation is preserved. This part can be
used as a general-purpose RF modulator, a variable attenu-
ator/phase shifter, or a remodulator. The amplitude can be
controlled from a maximum of −4.5 dB to less than −34.5 dB,
and the phase can be shifted continuously over the entire 360°
range. For maximum gain, the AD8341 delivers an OP1dB of
8.5 dBm, an OIP3 of 17.5 dBm, and an output noise floor of
−150.5 dBm/Hz, independent of phase. It operates over a
frequency range of 1.5 GHz to 2.4 GHz.
The baseband inputs in Cartesian I and Q format control the
amplitude and phase modulation imposed on the RF input
signal. Both I and Q inputs are dc-coupled with a ±500 mV
differential full-scale range. The maximum modulation band-
width is 230 MHz, which can be reduced by adding external
capacitors to limit the noise bandwidth on the control lines.
Both the RF inputs and outputs can be used differentially or
single-ended and must be ac-coupled. The RF input and output
impedances are nominally 50 Ω over the operating frequency
range. The DSOP pin allows the output stage to be disabled
quickly in order to protect subsequent stages from overdrive.
The AD8341 operates off supply voltages from 4.75 V to 5.25 V
while consuming approximately 125 mA.
The AD8341 is fabricated on Analog Devices’ proprietary, high
performance 25 GHz SOI complementary bipolar IC process. It
is available in a 24-lead, Pb-free LFCSP package and operates
over a −40°C to +85°C temperature range. Evaluation boards
are available.