A 28GHz Two-Way Current Combining Stacked-FET Power Amplifier in 22nm FD-SOI

We present a two-way current combining power amplifier (PA) for 28GHz wireless communication. To boost the saturated output power (PSAT) and maintain a high power-added efficiency (PAE), a differential 3-stacked transistors structure is used for the unit PA cell. The stability factor and the PAE are improved with capacitive neutralization and shunt inductor intermediate node matching. Reliability issues under a 2.4V supply voltage are relieved with properly designed biasing and gate capacitances. The PA is implemented in a 22nm FD-SOI technology with a chip core area of 0.21 mm2, Measurement results show that the PA achieves a power gain of 27dB and a PSAT of 21.7dBm with a maximum PAE of 27.1% at 28GHz. The output 1dB compression point (P1aB) is 19.1 dBm. Measured PAE at P1dB and 6dB power back-off are 23% and 10.3%, respectively.