A linear and efficient 1-bit digital transmitter with envelope delta-sigma modulation for 700MHz LTE

A highly linear and efficient 1-bit digital transmitter with envelope ΔΣ modulation (EDSM) is presented. Analyses and simulations reveal that the EDSM scheme is robust for distortion in output waveforms, and this has been experimentally verified using a CMOS EDSM IC and a GaN class-D PA for the 700-MHz band. The transmitter achieves an average η_D of 56.3% and an ACLR of -39 dBc for a 5-MHz BW and 6-dB PAPR LTE input without digital pre-distortion (DPD). Simple memoryless AM-PM correction is sufficient to improve ACLR to less than -45 dBc, indicating a lessening in required DPD.