A 225 GHz 90-nm SiGe Coupled-Line Coupler Gain-Boosted Low Noise Amplifier Operating Above fmax/2

This work presents two low noise amplifiers (LNA) operating at 225 GHz utilizing a novel coupled-line coupler gain-boosting technique that achieves increased power gain compared to conventional common-emitter stages with no additional power consumption. This technique is demonstrated and fabricated in a 90 nm SiGe BiCMOS process technology. The seven-stage and 15-stage LNAs operating at 225 GHz exhibit a measured gain of 5 dB and 11.7 dB, respectively. To the best of the authors’ knowledge, this work demonstrates the first implementation of a coupled-line coupler based gain-boosting technique for use in sub-THz amplifiers operating above fmax/2.