A Broadband Compact mm-Wave Series Doherty Power Amplifier Using Coupler Balun-Based Active Load Modulation Network in 65-nm CMOS

This paper presents a broadband, compact mm-Wave series Doherty power amplifier utilizing a coupler balun-based active load modulation network in 65-nm CMOS technology. The coupler-based baluns in the PA output network facilitate power combining, impedance matching, differential to single-ended conversion, and active load modulation. Adaptive biasing circuit further enhances the main/auxiliary PA cooperation. The proposed PA exhibits wideband PBO efficiency enhancement over a frequency range of 24 GHz to 36 GHz, achieving a fractional bandwidth of 40%. At the operating frequency of 29 GHz, the PA achieves a saturated power of 24.3 dBm and 32.4% peak PAE. At 7.5 dB PBO, the simulated PAE is 24.5%, demonstrating 1.68× efficiency enhancement compared to an ideal class-B PA with the same peak PAE at OP1dB.