A Broadband Variable Gain Low Noise Amplifier Covering 28/38 GHz bands with Low Phase Variation in 90-nm CMOS for 5G Communications

This paper presents a broadband, variable gain low noise amplifier (VGLNA) with low phase variation in 90-nm CMOS technology. The cascaded PMOS gain-boosting current steering VGA and a modified current steering VGA with the inductive phase-inversion network is utilized to compensate phase variation within the gain control range (GCR). In order to enhance overall gain of the circuit, gm-boosting and single-ended neutralization techniques are applied to the circuit. The VGLNA exhibits a peak gain of 21.4 dB at 37 GHz, 3-dB bandwidth covering from 26 to 30.5 GHz (band1) and 33.8 to 40.6 GHz (band2), respectively. An RMS phase error less than 4.3° and the maximum phase variation of 7.2° are achieved within the 9.8-dB gain control range (GCR) in the 3-dB bandwidth. The noise figure is 4.7 dB at 36 GHz in the maximum gain state. The chip consumes 17.9 mW dc power from 1-V voltage supply. To the author's knowledge, this circuit shows the highest figure-of-merit (FOM) among previous published CMOS VGAs with low phase variation design.