A highly linear dual-band Doherty power amplifier for femto-cell base stations

A power amplifier (PA) for a femto-cell base station should be highly efficient, linear and small. The efficiency for amplification of a high peak-to-average power ratio (PAPR) signal is improved by designing an asymmetric Doherty PA (DPA). The linearity is improved by applying third-order inter-modulation (IM3) cancellation method. For dual-band operation, a tunable switched capacitor is applied. A small size is achieved by designing the DPA using GaN MMIC process. The implemented dual-band DPA delivers a DE of 45.5/41.6%, ACLR of −35.6/−34.5 dBc, and a gain of 15.7/13.2 dB with an average output power of 35.3/33.7 dBm, respectively, for a 7.2 dB PAPR 10 MHz bandwidth LTE signal at 2.3 and 2.65 GHz.