A 2.5-GHz Multimode Broadband Bias-Segmented Power Amplifier With Linearity-Efficiency Tradeoff

This letter presents a highly linear, efficient, and fully integrated 2.5-GHz power amplifier (PA) for 4G long term evolution (LTE) applications in the 65-nm CMOS process. To improve the linearity, the segmented bias technique is adopted to increase the compression point of the PA. The power cell switching technique is also used to enhance the back-off efficiency of the PA. This technique enables the PA to operate in two zones: high power and medium power. The PA can be reconfigured in four modes to perform the desired performances and obtain the tradeoff between efficiency and linearity. The PA delivers a saturated output power of 29 dBm, a power gain of 30 dB, a power-added efficiency of 26%, and a 3-dB bandwidth of 780 MHz.