A 5–230-GHz 20-dB-Gain InP Matrix Amplifier Using Wideband Tapered Capacitors

This article presents the design of a wideband high-gain matrix amplifier (MA) comprising 12 amplifier cells in a two-tier six-stage ($2\times 6$) configuration. In the designed MA, wideband input signals are initially amplified by first-tier amplifier cells, generating forward and reverse waves that are then further amplified by second-tier cells, resulting in high gain and good output power over a broad frequency range. To further enhance the gain–bandwidth product, tapered capacitors are used to counteract line loss, therefore balancing the base voltages entering amplifier cells of the designed MA. The enhanced signal amplitudes along the MA’s middle line enable flexible designs and optimizations of tapered capacitors for gain, ripples, and power across a frequency range from a few GHz to sub-THz. The fabricated indium phosphide MA exhibits an average gain of 20 dB with ±2.5-dB ripple across a 5–230-GHz bandwidth. The measured input and output return losses are below −10 dB up to 190 GHz. The saturated power is averaged at 15.7 dBm over a 5–170-GHz bandwidth and is maintained above 14 dBm up to 180 GHz and 7.8 dBm up to 220 GHz. The output 1-dB compression point and the third-order intercept point peak at 13.8 and 24.8 dBm, respectively. The MA occupies a compact core area of 0.32 mm2and consumes 767 mW of DC power.