A Digital Envelope Modulator for an OFDM WLAN Polar Transmitter in 90 nm CMOS

A digital envelope modulator for an OFDM WLAN polar transmitter has been designed in 90 nm digital CMOS process for the 802.11 a/b/g standards. The digital modulator reaches an output power of -5 dBm for 54 Mbit/s using 64 QAM and fulfilling EVM specifications and in-band spectral mask requirements using 12.7 mW from a 1.2 V supply. When the digital modulator is combined with an off-chip PA, the output power increases to 20.4 dBm, while still fulfilling EVM specifications and in-band spectral mask requirements.