A 27–43 GHz CMOS Body-Biased Digital Current-Steering VGA With 4 Bit and Low Phase Shift

This letter presents a broadband digital-controlled variable gain amplifier (VGA) on 65-nm CMOS process. A body-biased digital current-steering topology is proposed to enlarge the gain control range (GCR) of the VGA under low supply voltage. For phased-array applications, a phase compensation network is added to minimize the phase shift during the gain tuning. The proposed VGA achieves a small-signal gain of 16.3/16.1 dB at 28/38 GHz with a 3-dB gain bandwidth from 25.5 to 46 GHz. The measured phase variation is 2.32°/4.8° with a GCR of 8.7/8.4 dB at 28/38 GHz. The phase variation of the VGA is less than 5° and the rms phase error is less than 1.46° over a wide frequency band of 27–43 GHz covering multiple 5G bands.