LAUSR

This paper presents a broadband THz power amplifier (PA) operating close to the maximum oscillation frequency (fmax) with proposed power combining and stagger-tuned gain boosting techniques. A compact broadband power combiner based on the compensated three-conductor transmission line (T-line) balun is proposed to simultaneously achieve broadband matching and power combining. A 4-stage stagger-tuned gain boosting amplifier operating closely to fmax is investigated to achieve a flattened power gain. Based on the proposed techniques, a broadband 300-GHz PA is implemented in a 130-nm SiGe BiCMOS process with ft/fmax = 350/450 GHz. It exhibits a peak gain of 15 dB and 3-dB bandwidth of 67 GHz (247314 GHz) with 2.5V supply voltage. At 290 GHz, a 5-dBm maximum output power POUT-MAX was measured with a 1-dB compressed output power OP-1dB of 3.3 dBm and a maximum PAE of 1.19%. The measured output power POUT-MAX and OP-1dB of the PA are 2.25 dBm and 0.63.3 over 250300 GHz, respectively. To the best of our knowledge, this PA achieves the highest operational frequency and widest bandwidth compared with other works in SiGe/CMOS process operating closely to fmax.