Design of a Broadband High-efficiency Power Amplifier by Using a Simple Method

Abstract

This letter proposes a simple method for designing broadband high-efficiency power amplifiers (PAs). Hybrid Class EFJ PAs theory is applied to achieve both high-efficiency and broadband at the same time. In order to make it more practical, a low-pass filter structure is introduced to design output matching circuits that satisfy the impedance conditions of Class EFJ PAs. Moreover, this paper exploits the characteristics of the transistor's output impedance, and selects three frequency points to design and synthesize a low-pass matching network. For validation, a PA working in 1.3-3.9 GHz is designed and fabricated based on CGH40010F transistor. The measurements illustrate that output power is from 40.5 dBm to 42.3 dBm and drain efficiency is between 61.3% and 71.2% at saturated level in the target frequency band. The ACLR is smaller than -28.4 dBc in the same frequency band.