An analog baseband chain of synthetic aperture radar receiver

An analog baseband chain for a synthetic aperture radar (SAR) receiver is presented in this paper. The proposed analog baseband chain consists of a 12^th-order bandpass filter (BPF) and a five-stage programmable gain amplifier (PGA). The BPF is composed of six cascaded Biquads and the switched-RC arrays are used to enable digital control of the passband in a frequency range from 0.68 to 9 MHz. The PGA employs binary-weighted switching array as pseudo-exponential function to achieve large dynamic range. Under 6-bit control words, the gain of the chain can be controlled and has 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. This analog baseband chain has been implemented in 65 nm CMOS technology embedding in a SAR receiver. The analog baseband occupies 0.35 mm² silicon area and consumes less than 16 mA current from a 1.2 V supply.