Polar Transmitter with Differential DSM Phase and Digital PWM Envelope

Bo Zhou, Shuli Liu
2014 JSTS Journal of Semiconductor Technology and Science  
A low-power low-cost polar transmitter for EDGE is designed in 0.18µm CMOS. A differential delta-sigma modulator (DSM) tunes a three-terminal voltage-controlled oscillator (VCO) to perform RF phase modulation, where the VCO tuning curve is digitally pre-compensated for high linearity and the carrier frequency is calibrated by a dual-mode lowpower frequency-locked loop (FLL). A digital intermediate-frequency (IF) pulse-width modulator (PWM) drives a complementary power-switch followed by an LC
more » ... ilter to achieve envelope modulation with high efficiency. The proposed transmitter with 9mW power dissipation relaxes the time alignment between the phase and envelope modulations, and achieves an error vector magnitude (EVM) of 4% and phase noise of −123dBc/Hz at 400kHz offset frequency.
doi:10.5573/jsts.2014.14.3.313 fatcat:gwsitp54vzfcpmb6hbkuvenaxi