Multi-standard wideband OFDM RF-PWM transmitter in 40nm CMOS

A fully digital 0.9GHz-2.6GHz multimode modulator based on the principle of RF-PWM is presented. It makes use of a delay-line based phase modulator which delays an incoming LO-signal with a resolution of 4ps. The modulator is designed to drive highly efficient switching power amplifiers and support carrier frequencies over a wide range. The modulator has been implemented in 40nm CMOS technology. It achieves an EVM of better than -29dB for a 802.11g 64-QAM OFDM signal. It has also been tested with 40MHz single carrier 64-QAM modulated signals. The measured ACPR is below -30dB up to 2GHz and possible improvements are demonstrated.