Transformer based dual-power-mode CMOS power amplifier for handset applications

A fully integrated transformer based dual-power-mode CMOS power amplifier (PA) is implemented. The proposed architecture provides enhanced back-off efficiency with simple circuit topology. With broadband characteristic of the transmission line transformer, the PA delivers good performance across the 1.7-2.0 GHz frequency band. The PA with a 3.5 V supply voltage has gains of 14.5-16.2 dB and 10-10.5 dB in high power mode (HPM) and low power mode (LPM), respectively. The linear average output power for long-term evolution signals having 10-MHz bandwidth and 7.5 dB peak-to-average power ratio is 26/20 dBm with a PAE of 31.6%-33.8%/20.8%-26.5% across the 1.7-2.0 GHz frequency in the HPM/LPM.