A single-chain multiband reconfigurable linear power amplifier in SOI CMOS

A multiband linear CMOS power amplifier (PA) is developed to cover multiple LTE bands from 800 to 2000 MHz using a single PA core. The single-chain PA is based on a two-stage design using stacked-FET cells, and is designed to support any combinations of low/high dual bands out of five popular 3G/4G bands (Band 1/2/4/5/8). To avoid the performance degradation by covering such a wide bandwidth using a single PA-core, the frequency reconfigurability has been applied to the stacked-FET cells, interstage matching as well as the output matching. To further enhance the linearity and efficiency, a phase-based linearizer is employed and reconfigured according to the operating frequencies. W-CDMA test on the fabricated PA shows adjacent channel leakage ratios (ACLRs) better than -39 dBc up to the rated linear power of 28.5 dBm and power-added efficiencies (PAEs) higher than 40.7% and 46% for high- and low- frequency band groups, respectively. Compared with the dedicated PAs using the same process, PAE degradation is limited to 1.6 ~ 3.3%. To our knowledge, this work is among the best results from the single-chain PAs for 3G/4G mobile applications.