A 190MHz 4nV/√Hz analog baseband chain of Synthetic Aperture Radar (SAR) receiver

An analog baseband chain for a Synthetic Aperture Radar (SAR) receiver implemented in a 130nm CMOS technology is presented in this paper. Occupying 0.23mm
²
of silicon area, the baseband chain consists of a three-stage Variable Gain Amplifier (VGA), a 5th-order gm-C Low Pass Filter (LPF) and an Output Buffer (OBUF). The gain of the chain can be controlled by tuning the control voltages of the VGA and has a range from 25dB to 34dB. In addition, the LPF has an 8dB gain to meet the required dynamic range of the following block. The bandwidth of the LPF is programmable from 120MHz to 190MHz by means of capacitor matrices. The chain, which uses a 1.2V supply voltage, achieves 4nV/√(Hz) of input-referred noise density and -42dBV in-band IIP3.