45–100-GHz UWB and W-Band High-Efficiency SiGe Power Amplifiers With 20-/20.1-dBm P sat and 17.3%/22.4% Peak PAE

This article presents two stability- and linearity-enhanced power amplifiers (PAs) in a 0.13- $\mu $ m SiGe BiCMOS technology. The ultrawideband (UWB) PA comprises four differential cascode (CC) stages with a two-way differential power combining architecture at the last stage. The W-band PA originates from the last two stages of UWB PA and aims for higher power-added efficiency (PAE). A metal–oxide–metal (MOM) capacitor-based stability-enhancement technique and an adaptive-bias circuit are proposed to improve the stability and linearity of the two PAs, respectively. A compact power splitter is utilized between the last two stages to reduce the chip area. The UWB PA achieves a measured 3-dB gain bandwidth (BW) from 45 to 100 GHz with a peak gain of 30.6 dB at 94 GHz. The 3-dB saturated output power ( $P_{\mathrm {sat}}$ ) BW ranges from 62 to 100 GHz with a peak $P_{\mathrm {sat}}$ of 20 dBm and a peak PAE of 17.3% at 92 GHz. The peak output-referred 1-dB compression point (OP ${}_{\mathbf {1 dB}}$ ) is 16.5 dBm at 92 GHz. The W-band PA achieves a measured 3-dB gain BW from 80 to 97 GHz with a peak gain of 21.4 dB at 90 GHz. The 3-dB $P_{\mathrm {sat}}$ BW is from 76 to 100 GHz with a peak $P_{\mathrm {sat}}$ of 20.1 dBm and a peak PAE of 22.4% at 94 GHz. The peak OP ${}_{\mathbf {1 dB}}$ is 16.7 dBm at 96 GHz. In addition, modulation measurements show that both the UWB and W-band PAs support 18–Gb/s 64-quadrature-amplitude modulation (QAM) at 94 GHz with error-vector magnitudes (EVMs) of −27.3 and −29.6 dB, respectively.