Broadband variable gain amplifier with very low phase variation in 28nm CMOS

A broadband variable gain amplifier (VGA) with low phase variation versus control range is presented in this work. The measured phase variation of less than 3.5° versus the high gain control range of 25dB make this VGA a suitable building block for multi-antenna front-ends. The circuit shows a large 3 dB bandwidth of 13GHz and therewith covers multiple ISM frequency bands. The chip is implemented using a Global Foundries (GF) 28 nm bulk CMOS process and the active area amounts to only 31μm×70μm. It consumes maximum 4.2mA from a supply of 1.8 V.