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RF Vector Modulator
700 – 1000 MHz
Preliminary Technical Data
AD8340
Rev. PrF 1/23/2004
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infringements of patents or other rights of third parties that may result from its use.
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FEATURES
Cartesian Amplitude and Phase Modulation
Frequency Range 700 MHz – 1.0 GHz
Continuous Magnitude Control of 0 to –30 dB
Continuous Phase Control of 0 to 360 Degrees
Output Third Order Intercept +22 dBm
Output 1 dB Compression Point +12 dBm
Single Supply Voltage 4.75 V – 5.25 V
Adjustable Modulation Bandwidth up to 230 MHz
Fast Output Power Disable
Output Noise Floor –148 dBm/Hz
Differential I & Q Control Inputs
APPLICATIONS
RF PA Linearization/RF Predistortion
Amplitude and Phase Modulation
Variable Impedance-Matched Attenuator and Phase Shifter
Smart Antennas
CDMA2000, GSM/EDGE Linear Power Amplifiers
GENERAL DESCRIPTION
The AD8340 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 attenuator/phase
shifter or a re-modulator. The amplitude can be controlled from a
maximum of 0 dB to less than –30 dB and the phase can be shifted
continuously over the entire 360 degree range. For 0 dB gain, the
AD8340 delivers a P1dB of 12 dBm, an OIP3 of 22 dBm and an
output noise floor of –148 dBm/Hz, independent of phase. It can
operate over a frequency range from 700 MHz to 1.0 GHz with
gain and phase flatness less than 0.2 dB and 0.5 degree.
The base-band 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
FUNCTIONAL BLOCK DIAGRAM
Figure 1. AD8340 Functional Block Diagram
full-scale range. The maximum modulation bandwidth 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 ohms over the operating frequency
range. The DSOP pin allows the output stage to be disabled quickly
in order to protect subsequent stages from over-drive. The AD8340
operates off supply voltages from 4.75 to 5.25 V while consuming
130 mA.
The AD8340 is fabricated on Analog Devices’ proprietary, high
performance 25 GHz SOI complementary bipolar IC process. It is
available in a 24-pin CSP package and operates over-a -40 to +85
°C temperature range. Evaluation boards are available.
