Summary
This paper presents a K‐band high‐gain Class‐A power amplifier (PA) with the two‐way combining approach in GSMC 130‐nm radio frequency (RF) complementary metal oxide semiconductor (RF CMOS). At the input, a slow‐wave transmission‐line transformer (S‐TLT) matching network is proposed for simultaneously realizing the impedance transformation and the single‐ended RF signal to differential conversion. Transmission‐line transformers (TLTs) are employed between the stages for coupling and inter‐stage matching. To improve the output power and efficiency, the placing and routing of the transistor layout are considered carefully for power stages to reduce the interconnecting and overlapping parasitics significantly. The PA has been fabricated and achieved good matching at 25 GHz, power gain of 17.8 dB, saturated output power of 14.9 dBm, output 1‐dB compression point of 12.4 dBm, and power added efficiency of 13.7% at a supply voltage of 1.5 V.