Design strategy of concurrent multi-band Doherty power amplifier

Abstract

This paper proposes design methodologies of concurrent multi-band Doherty power amplifiers (PAs) based on multi-band impedance inverting networks and multi-band phase offset lines (POLs). Design procedures for implementing such multi-band impedance inverting networks and multi-band POLs at arbitrary frequencies are presented here. For validating the design procedures, tri/quad-band Doherty PAs are designed, fabricated and tested using continuous wave (CW) and modulated signals in discrete mode and concurrent mode. The tri-band Doherty power amplifier (DPA) is implemented at 1600, 1900 and 2200 MHz. CW signal measurement of tri-band DPA shows an efficiency of 46%, 40% and 42%, respectively, around 6 dB output power back-off (OPBO). The quad-band DPA is implemented at 1600, 1960, 2140 and 2350 MHz. Measured results using CW signal shows an efficiency of 40%, 37%, 30% and 31%, respectively, around 6 dB OPBO.