A 26.8 dB Gain 19.7 dBm CMOS Power Amplifier Using 4-way Hybrid Coupling Combiner

This letter presents a novel compact 4-way hybrid coupling combiner applied in an mm-wave CMOS power amplifier (PA) design with wideband, large output power and high gain. Basing on the principle of both series and parallel combination concurrently working in a concentric distributed active transformer, the size of a 4-way power combiner can be dramatically reduced. Using the proposed power combiner, a four-stage common source PA is implemented in 65 nm CMOS process. In each stage, inductive source degeneration is employed to enhance transistor stability without reducing maximum stable gain. The measurement results show that the PA can offer 26.8 dB linear gain with 3 dB bandwidth of 51-67 GHz. At 1.2 V/1.4 V external supply voltage, the PA is able to deliver 17.5 dBm/19.7 dBm Psat with 10.3%/13.4% power added efficiency (PAE). The chip size of the PA is only 0.32 mm².