A 4×Two-Way mm-Wave Doherty CMOS PA

Abstract

This article introduces a 4 x 2 -way Doherty power amplifier (PA) tailored for millimeter-wave (mm-wave) 5G applications. It incorporates an advanced output combiner that consists of four differential 2-way Doherty networks, two quadrature hybrid couplers (QHCs), and a balun to enhance the output power P_out and improves power back-off (PBO) efficiency. Realized in 40 nm CMOS bulk technology with a core area of 1.54 mm², the prototype delivers a saturated power/peak gain surpassing 25.2 dBm/25.5 dB, and it demonstrates a drain efficiency (DE) exceeding 17.5%/10% at 0 dB/6 dB PBO across a 26–32 GHz band. The proposed mm-wave PA achieves error vector magnitude (EVM)/adjacent channel leakage ratio (ACLR) values of −25 dB/−33 dBc for a 2 GHz 64-quadrature amplitude modulation (QAM) orthogonal frequency-division multiplexing (OFDM) signal with 9.6 dB PAPR, operating at an average output power (P_avg) of 11.3 dBm with an average drain efficiency (DE_avg) of 4% without using digital predistortion (DPD). For a 50 MHz 1024-QAM OFDM signal with 10 dB PAPR, it achieves a P_avg/DE_avg of 7.2 dBm/2% with EVM/ACLR of −35 dB/−42 dBc without DPD.