Abstract
This paper presents a 210-to-250 GHz differential single-stage quad-stacked power amplifier (PA) for sub-terahertz communications. The proposed amplifier utilizes a quad-stacked Bipolar Junction Transistor (BJT) topology with a combination of inter-nodal inductors between adjacent transistors and BASE inductors for voltage swing enhancement and amplifier gain boosting. The differential input/output ports are converted to single-ended for testing purposes with customized Marchand Baluns. Verified by full-EM and circuit-level co-simulation, the PA achieves an operation frequency of 210 to 250 GHz with a gain better than 12.5 dB, a maximal gain of 15.5 dB at 240 GHz, a saturated output power P SAT of 10.5 dBm, and an output 1-dB compression point OP 1dB of 6.6 dBm, and power consumption of 405 mW. The calculated power-added efficiency PAE at OP 1dB is 1.1%. Compared to similar SiGe sub-THz PAs, this work only shows the advantage of small core circuit area of 0.01 mm 2 .