Datasheet Analog Devices AD603SQ/883B

Low Noise, 90 MHz
Variable Gain Amplifier
AD603 Data Sheet The decibel gain is linear in dB, accurately calibrated, and stable
over temperature and supply. The gain is controlled at a high
impedance (50 MΩ), low bias (200 nA) differential input; the
scaling is 25 mV/dB, requiring a gain control voltage of only
1 V to span the central 40 dB of the gain range. An overrange
and underrange of 1 dB is provided whatever the selected range.
The gain control response time is less than 1 μs for a 40 dB change. FEATURES
Linear-in-dB gain control
Pin-programmable gain ranges
−11 dB to +31 dB with 90 MHz bandwidth
9 dB to 51 dB with 9 MHz bandwidth
Any intermediate range, for example −1 dB to +41 dB
with 30 MHz bandwidth
Bandwidth independent of variable gain
1.3 nV/√Hz input noise spectral density
±0.5 dB typical gain accuracy The differential gain control interface allows the use of either
differential or single-ended positive or negative control voltages.
Several of these amplifiers may be cascaded and their gain
control gains offset to optimize the system SNR.
The AD603 can drive a load impedance as low as 100 Ω with
low distortion. For a 500 Ω load in shunt with 5 pF, the total …