A 2-18GHz Digitally Controlled Variable Gain Amplifier with Low Phase Shift and Large Dynamic Range

This paper presents an ultra-wideband digitally controlled variable gain amplifier using 55nm CMOS technology. The VGA consists of a gain block and a digital step attenuator (DSA). The high frequency gain is compensated in the gain block and a phase compensation structure is added to the attenuator unit to reduce additional phase shift. The proposed VGA can operate from 2 to 18 GHz with a gain range of -15.5 dB to 16 dB, a 6-bit step of 0.5 dB, input and output return loss of better than 10 dB and maximum phase shift error of less than 4.3°. In maximum gain mode, the minimum noise factor is 3.9dB and IP1dB is -21dBm. The chip size is 936 × 560 um ² .