3.2-mW Ultra-Low-Power 173-207-GHz Amplifier With 130-nm SiGe HBTs Operating in Saturation

This article presents an ultra-low-power silicon germanium heterojunction bipolar transistor (SiGe HBT) amplifier operating at 200 GHz. The amplifier consists of three cascaded gain-cell stages and was implemented in an experimental 130-nm SiGe HBT technology with peak $f_{{\textrm {T}}}/f_{\text {max}}$ of 460/600 GHz. In order to achieve the demonstrated extremely low dc power dissipation, the circuit was designed with transistors operating at forward-biased base–collector junction voltage ( $V_{\text {BC}}$ ). With 1.3-V supply voltage ( $V_{\text {BC}}\approx 0.2$ V), this amplifier exhibits a peak gain of 23.5 dB at 180 and 205 GHz with 34-GHz 3-dB bandwidth (BW) from 173 to 207 GHz, consuming 3.2-mW static dc power. Even with a supply voltage of 0.7 V ( $V_{\text {BC}} \approx 0.5$ V), this amplifier still operates with a peak gain of 18.3 dB at 175 GHz, dissipating an extremely low dc power of 1.73 mW. Compared with the previously reported low-power amplifiers operating around 200 GHz, this article achieves the highest linear gain relative to the dc power consumption with an improvement factor of ten, as well as highly competitive performances in terms of noise figure and 3-dB BW.