A K-band transformer based power amplifier with 24.4-dBm output power and 28% PAE in 90-nm CMOS technology

A fully integrated K-band transformer based power amplifier with neutralization technique is proposed and fabricated in 90-nm CMOS technology. Several cascode cells are combined together as differential power cells. On-chip transformers and current combing topology are used to combine amplifiers as well as to reduce the problem of output power loss. In order to improve the overall stability, neutralization structure is utilized in the combined cascode cell. The measurement results demonstrate 14.1-dB small-signal gain, saturated power (Psat) of 24.4 dBm, and output 1-dB compression point (ÖPrdB) of 21.7 dBm at 24 GHz. The peak power added efficiency (PAE) achieved by this PA at 24 GHz is 28%. The chip size is 0.526 mm
²
with all pads. To the authors' knowledge, this circuit presents a superior power and efficiency performance compared with the reported K-band CMOS PAs.