An mm-Wave Multi-Mode Asymmetric Power Amplifier With Back-off Efficiency Enhancement

Abstract

This paper presents a multi-mode asymmetric power amplifier (MMA-PA) with back-off efficiency enhanced. The back-off efficiency is improved without a lossy impedance inverter or signal separator which is used in conventional Doherty or outphasing amplifiers. The design considerations are provided in detail. In addition, the proposed MMA-PA operates in three different modes according to the input power level. The PA is fabricated in a 65-nm bulk CMOS technology. In the high-power (HP) mode, the MMA-PA exhibits a small-signal gain of 18.4 dB at 30 GHz and a 3-dB bandwidth of 4.5 GHz from 27.7 to 32.2 GHz. The output saturation power (P sat ) and 1-dB compression power are 16.7 and 15.1 dBm, respectively. While the peak power-added efficiency (PAE) is 24.7 %, the 6-dB back-off PAE keeps a high value of 14.1 %. In the medium-power (MP) mode, P sat and peak PAE are 12.3 dBm and 21 %, respectively with a similar gain of 18.9 dB. In the low-power (LP) mode, the gain, P sat and peak PAE are 11.5 dB, 7.5 dBm and 16.5 %, respectively. With a 100-MHz 64-QAM OFDM signal following the 3GPP 5G NR standard, the average output power in the HP mode is 6 dBm with EVM of −26 dB and ACLR < −34 dBc. In the MP and LP modes, the average output power are 3.3 and 1.1 dBm, respectively with EVM of −26.6 and −26.1 dB.

Theoretical and Experimental Analysis of Reversed Uneven Power Splitting Technique in GaN MMIC Doherty Power Amplifiers

“…When the input power is evenly split between both amplifiers, the basic configuration leads to inadequate load modulation due to insufficient current in the class-C peaking amplifier [13]. To address this issue without the need for additional circuitry, two effective methods have been demonstrated: the asymmetric structure [13][14][15][16][17][18] and uneven power splitting (UPS) [18][19][20].…”