Wideband High-Gain Amplifiers in 45-nm CMOS SOI Operating at 0.56fmax: An Analytical Approach on Reversed Feedback Amplifiers

This article presents a novel feedback amplifier (FBA) architecture to realize sub-terahertz, high-gain, wideband amplifiers. The proposed topology employs a gain-boosting technique in each amplifier cell to increase the gain of a multistage amplifier over a broad bandwidth (BW) when cascaded with a conventional FBA (CFBA). The amplifier cell provides a close-to- ${G} {_{\max }}$ gain even when passive losses are present. The multistage amplifier topology is compact and does not need inter-stage matching networks (ISMNs) between its internal cells. Two proof-of-concept G-band amplifiers were implemented in a 45-nm CMOS silicon-on-insulator (SOI) process to verify the feasibility of the proposed architecture. These prototypes achieve peak gains of 14 and 20.4 dB, peak saturated output powers of 6 and 6.1 dBm, power-added efficiencies (PAEs) of 3.8% and 3.7%, and minimum noise figures (NFs) of 6.2 dB over 156–193.8 and 157.4–194.2 GHz, respectively. To the best of the authors’ knowledge, the presented amplifiers in this work obtain the highest BW among the CMOS amplifiers operating at near- ${f} {_{\max }}$ .