A high gain decibel-linear programmable gain amplifier of synthetic aperture radar receiver

A high gain decibel (dB)-linear programmable gain amplifier (PGA) for a synthetic aperture radar (SAR) receiver is presented in this paper. The proposed PGA employs binary-weighted switching array as pseudo-exponential function to achieve large dynamic range. A current compensation circuit is proposed in fine gain step cell to decrease gain step error. This PGA has been implemented in 65 nm CMOS technology embed ding in a SAR receiver. Measurement results show that the proposed PGA exhibits a dB-linear gain range of 60 dB from 10.47 to 69.63 dB with a gain error of less than ±0.39 dB, a input 1-dB compression point (IP-1dB) of -67.8 to -18.4 dBm, a 3-dB bandwidth of 0.8 to 50 MHz at the maximum gain while consuming less than 5.4 mA from a 1.2 V supply.