A 64.5-88 GHz Coupling-Concerned CMOS LNA with >10 dB Gain and 5 dB Minimum NF

This paper presents a differential 64.5-88 GHz wideband low-noise amplifier (LNA) in a 55-nm CMOS technology. The LNA is consisted of two common-source (CS) stages and one cascode stage. To achieve a wide bandwidth (BW), an interstage coupling network scheme utilizing step-up transformers and co-optimizing the interstage transimpedance responses is developed. A new transformer-based dual-coupling (TBDC) $gm$-boosted topology is proposed to simultaneously achieve high gain and low noise. In addition, capacitive neutralization and common-gate-shorting (CGS) techniques are utilized to improve gain and stability. The LNA achieves a peak gain of 15 dB, a wideband gain of >10 dB over 64.5-88 GHz, a $S_{11}$ of <-10 dB over 60–90 GHz, and a minimum noise figure of 5 dB, while consuming 72.7 mW power. The input PldB is -12.2 dBm at 70 GHz and -12.8 dBm at 80 GHz, respectively.