Compact 138-GHz amplifier with 18-dB peak gain and 27-GHz 3-dB bandwidth

This paper presents a wideband differential amplifier operating at 138 GHz in 40-nm CMOS. It is composed of five differential common source stages with cross-coupled capacitors. A small-signal gain of 18 dB at 138 GHz and a 3-dB bandwidth of 27 GHz are achieved. It consumes 75 mW from a 0.94-V voltage supply. The die area with balun and pads is 945 × 842 μm2 and the core size not including input/output matching networks is 201 × 284 μm2. The small core area is realized by using a refined "fishbone" layout technique.