A W-Band Wide 1-dB Bandwidth Power Amplifier With Parallel Inductance Enhanced Coupling Transformer in 0.13-μm SiGe BiCMOS Technology

This article presents a W-band wide 1-dB gain bandwidth power amplifier (PA) with two novel type parallel inductance enhanced coupling transformers (PIECTs). The proposed PIECT type 1 and type 2 extremely improve the upper limitation of the coupling coefficient (<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i>) in advanced silicon-based process technologies alleviating design challenges for broadband matching networks in W-band and beyond. Furthermore, the theoretical models for their enhanced <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> are derived and the corresponding optimization approach is presented. The results show that the proposed PIECT type 1 can provide 52% improvement in <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">k</i> compared with the traditional transformer (TTF) and the proposed PIECT type 2 further increases by 24%. In addition, a novel fin-ground structure is proposed to mitigate the signal crosstalk, and it enhances the output 1-dB compression point (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{OP}_{\mathrm {1\, dB}}$ </tex-math></inline-formula>) and peak power-added efficiency (PAE) by 0.5 dBm and 2%, respectively. The proposed PA is fabricated using 0.13-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $ </tex-math></inline-formula>m SiGe BiCMOS technology with a core area of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$291\times 974~\mu \mathrm{m}^{2} $ </tex-math></inline-formula>. The measurement results show that the 1-dB gain bandwidth is approximately 16 GHz across 83–99 GHz and the 3-dB gain bandwidth reaches to 21 GHz from 80.5 to 101.5 GHz, corresponding to the fractional bandwidth (FBW) of 17.0% and 22.3%, respectively. Moreover, at 94 GHz, the gain, saturated output power, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\text{OP}_{\mathrm {1 \,dB}}$ </tex-math></inline-formula>, and peak PAE are 22.2 dB, 16.1 dBm, 15.2 dBm, and 12.3%, respectively.