A 90nm CMOS Doherty Power Amplifier with Integrated Hybrid Coupler and Impedance Transformer

Abstract

An OFDM capable Doherty PA is implemented in 90 nm CMOS with integrated quadrature hybrid and impedance transformer. The two amplifiers are optimized to minimize AM-PM distortion. The PA achieves 25 dBm Psa, using 1.4 V supply with 24% PAE, and operates over 1 GHz of frequency range (from 4 GHz to 5 GHz). 3 dB to 6 dB back-off from P1dB is required to achieve -25 dB measured EVM across this band, making it suitable for WLAN and WiMAX applications. The measured AM-PM distortion varies from 4deg to 12.5deg across the 1 GHz range.