CMOS dynamic supply switching power amplifier for LTE applications

This paper presents a CMOS power amplifier (PA) based on a dynamic supply switching technique for long-term evolution (LTE) applications. The PA integrated circuit includes a supply modulator which consists of two DC-DC converters and a switching circuit for dynamic supply switching (DSS) operation. The supply modulator dynamically supplies either low-or high DC voltage to the drain of the PA. To improve the efficiency for low average output power levels, the low and high DC voltages are adjusted at the outputs of the DC-DC converters according to the average output power. For the 16-QAM LTE signal at a frequency of 1.75 GHz, the DSS PA exhibited a high power-added efficiency (PAE) of 35.8% and an adjacent channel leakage power ratio (ACLR) of -34 dBc at an average output power of 21.8 dBm. This PAE is 3.4% points higher than that of the standalone PA. With adjusted DC voltages, a PAE of 29.42% was achieved at an average output power of 17 dBm while maintaining an ACLR of -34 dBc. This is 13.38% points higher than that of the standalone PA at the same output power.