Broadband High-Efficiency mm-Wave 24-42.5 GHz SiGe PA Design Using Stacked Versus Cascaded Topologies

We present in this work two versions of broadband highly efficient millimeter-wave power amplifiers (mm-Wave PAs) design in a 90-nm SiGe technology. Both the 2-stage cascaded common-emitter (CE) PA and the 2-stacked PA can achieve wide 3-dB bandwidth from 20-45 GHz with P
_OUT
above 16-19 dBm in post-layout simulation, but the 2-stacked PA consistently outperforms the cascaded PA in power-added efficiency (PAE), achieving peak PAE at 36.9% (30 GHz) with max PAE remaining above ~30% from 24-45 GHz, which is ~8%-18% better than those of the 2-stage cascaded PA, thus suggesting the stacked PA topology to be rather attractive for high-efficiency broadband mm-wave applications.