A 1–21-GHz, 1.95–3.1-dB NF Ultra-Wideband LNA With <i>Gₘ</i> -Assisted-Feedback Noise Suppression Achieving 140-Gb/s Data Rate in 40-nm CMOS

This article presents an ultra-wideband (UWB) low noise amplifier (LNA) with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula>-assisted-feedback noise suppression technique for multi-band wireless communication. Compared with the traditional resistive feedback (RF) and source-follower feedback wideband LNAs, the proposed LNA blocks the noise current from the feedback resistor with a simple additional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula>-cell, thus alleviating the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{11}$ </tex-math></inline-formula>-NF design tradeoff in the traditional structures. A source coupling transformer is also utilized to create <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$g_{m}$ </tex-math></inline-formula>-boosting and maintain a wideband flat gain. Fabricated in a 40-nm bulk CMOS process, the LNA prototype achieves a measured operating bandwidth (BW) of 1–21 GHz, measured NF of 1.95–3.1 dB, and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$S_{21}$ </tex-math></inline-formula> of 20.6–22.4 dB, while consuming 21.6 mA from a 1.2-V power supply. It also supports UWB modulation signals with a data rate of 140 Gb/s. The proposed LNA reports the lowest NF among the recently reported bulk CMOS UWB LNAs.