A 24-GHz CMOS Transformer-Based Three-Tline Series Doherty Power Amplifier Achieving 39% PAE

TL;DR

This paper introduces a CMOS-based three- Tline series Doherty PA for broadband mm-wave applications, achieving high efficiency and power output suitable for next-generation wireless systems.

Contribution

It presents a novel transformer-based Tline series Doherty PA with impedance-scaling for broadband operation in CMOS technology.

Findings

Bandwidth from 22 to 32.5 GHz with -3 dB gain

Peak PAE of 39% at saturation

PAE remains above 24% at 6 dB back-off

Abstract

This paper presents a transformer-based three- transmission-line (Tline) series Doherty power amplifier (PA) implemented in 65-nm CMOS, targeting broadband K/Ka-band applications. By integrating an impedance-scaling network into the output matching structure, the design enables effective load modulation and reduced impedance transformation ratio (ITR) at power back-off when employing stacked cascode transistors. The PA demonstrates a -3-dB small-signal gain bandwidth from 22 to 32.5 GHz, a saturated output power (Psat) of 21.6 dBm, and a peak power-added efficiency (PAE) of 39%. At 6dB back-off, the PAE remains above 24%, validating its suitability for high- efficiency mm-wave phased-array transmitters in next-generation wireless systems.