Novel reconfigurable fundamental/harmonic matching network for enhancing the efficiency of power amplifiers

This paper presents a novel tunable matching network scheme suitable for the design of electronically reconfigurable microwave circuits. These circuits enable the development of high performance and frequency agile RF front-end modules for multi-band and multi-carrier radios in cognitive wireless networks. In this paper, the tunable matching network includes a harmonic tuning feature essential to the design of high efficiency power amplifiers (HEPA). Two different types of electronic tunable devices, namely MEMS switches and semiconductors varactors, are used in the realization of the reconfigurable matching networks proof of concepts prototypes designed to operate in the band spanning from 1.8GHz to 2.7GHz. Both prototypes revealed a broad impedance tuning range (|Γ|> 0.85) along with low insertion loss (IL<;1.3dB for high |Γ|). The varactor-based matching network was used to modulate the load impedance of a 10Watt HEPA operating in Class F^-1. The control of the load impedance versus the input signal power allowed for significant efficiency improvement compared to conventional Class F^-1 PA which attained about 18% at 6 dB back-off.