A Ferroelectric-Capacitor-Based Tunable Matching Network for Quad-Band Cellular Power Amplifiers

A tunable matching network (TMN) based on ferroelectric capacitors for cellular power-amplifier applications was designed, fabricated, and tested. When the matching network is operated for GSM850/900 frequency bands, the input impedance varied from 3.44-j1.87 to 3.55-j0.02 Omega with a power gain variation of -1.35 to -1.62 dB. When the circuit is operated for digital communication system/personal communication system/wideband code division multiple access frequency bands, the input impedance varied from 4.28-j0.06 to 4.31+j0.97 Omega with a power gain variation of -2.05 to -1.79 dB. The nonlinearity of the TMN was also characterized on an on-wafer load-pull system using a 1.95-GHz test signal with CDMA2000 and high-speed downlink packet access modulation strings