A 60GHz variable-gain LNA in 65nm CMOS

A four-stage 60GHz low-noise amplifier is implemented in 65nm CMOS with nMOS f
t
of 210GHz. The LNA incorporates a reflection-type attenuator to provide variable gain with improved linearity in low-gain mode and a tunable notch filter for image rejection. The LNA, which consists of two common-source stages followed by two cascode stages, consumes 30.8mW and achieves 5.9dB NF and 15dB gain at 60GHz. The variable attenuator provides 1OdB of gain variation with the input-referred 1dB compression point of the LNA being −15.1dBm in high gain mode and −6dBm in the low-gain mode. Each tunable notch filter stage provides an additional 8dB attenuation of 37GHz image signals, with the four-stage LNA achieving more than 35dB image-rejection.