An 830-MHz CMOS Switch-Mode Power Amplifier Under Time-Multiplexing Outphasing Operation

An 830-MHz CMOS switch-mode power amplifier (SMPA) has been demonstrated under our proposed time-multiplexing Outphasing (TMO) operation. The TMO encoding waveform has constant envelope, which is suitable for an SMPA. The noise level close to the carrier is quite low compared with conventional envelope delta-sigma modulation and envelope pulse-width-modulation spectra although spurious products are emerged at the one-fifth of the carrier frequency away. For demonstration, a differential voltage-mode class-D power amplifier was fabricated using 45-nm SOI CMOS technology with an off-chip reconstruction filter. In the single-tone test, the peak output power of 15.4 dBm and peak overall efficiency of 54.4% are achieved. An 802.11ah like signal with the peak-to-average ratio of 8 dB is delivered, where the in-band noise floor of the TMO spectrum is approximately 20 dB lower compared with envelope delta-sigma / pulse-width modulated spectra.