A 25.6 dBm wireless transmitter using RF-PWM with carrier switching in 130-nm CMOS

A wireless transmitter using RF pulse-width-modulation (PWM) with carrier switching is introduced. The proposed approach overcomes the dynamic range limitation of PWM at radio frequencies by utilizing carrier switching between fundamental and half-fundamental frequencies, depending on the signal level to be transmitted. This allows for transmission of signals with large peak-to-average power ratio (PAPR) such as OFDM. The efficiency is also improved in the power back-off region due to reduced switching losses in the half-fundamental mode. The transmitter has been implemented in a 130-nm CMOS process. The measured peak output power and power-added-efficiency (PAE) are 25.6 dBm and 34%, respectively. While driving 802.11g 64-QAM OFDM signals, the average output power is 18.3 dBm and the PAE is 16% with an EVM of -25.5 dB.