A 60-GHz, 15-dB Gain Range Digitally Controlled Phase-Inverting VGA With 0-dBm OP₁ dB and 3° Phase Variation in 65-nm CMOS

Abstract

A 60-GHz digitally controlled phase-inverting variable gain amplifier (PIVGA) is presented, with a gain control range from -9.4 to 6 dB, and a 180° phase inversion. Four digitally controlled nMOS switch arrays in the proposed PIVGA are used as a current-steering stage, which can reduce control complexity of the current-steering stage and reduce phase variation as well. A transformer to decouple input stage and current-steering stage instead of the nMOS transistor cascode topology is used to improve linearity. The PIVGA prototype is implemented in a 65-nm CMOS technology. Measured results show a gain range from -1 to 6 dB with a 0.5-dB linear-decibel fine gain step, an OP <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</sub> dB of 0 dBm, and a dc power consumption of 25 mW. As the gain is programmed over the entire 53-63 GHz, the phase shifts only varies by less than 3°.