A Wideband SiGe D-Band Power Amplifier with 17.4 dBm Peak Output Power Featuring a Transformer-Based Load

In this paper, we present a D-band (110-170 GHz) power amplifier (PA) achieving a maximum output power of 17.4 dBm at a center frequency of 140 GHz. The PA exhibits a large 3 dB bandwidth of 53 GHz, reaching from 115 GHz to 168 GHz. Over the entire D-band, the saturated output power only varies by 5 dB. The circuit is designed in Infineons B12HFC 90 nm SiGe BiCMOS technology with an ft and fmax of 300 GHz / 500 GHz, respectively. The power amplifier consists of one gain and one power stage, which both utilize a fully differential cascode topology. A four-way power combining topology that takes advantage of transformer-based loads was designed. A maximum small signal gain of 18.2 dB was measured. S-parameter measurements and calculated stability factors prove the amplifier's stability.