PWM coding and filtering of an OFDM envelope signal in a C band EER transmitter architecture

This paper concerns the simulation of OFDM envelope path in an EER architecture. The envelope information is clipped to reduce the dynamic variation, PWM coded and low-pass filtered. The PWM coding is simulated with a modified Schmitt trigger with different hysteresis values. The reference voltage shape and frequency choice are discussed. The low-pass filter parameters depend on the frequency of the reference voltage signal and are summarized. The conclusion shows the tradeoff between spectral response and EVM results for choosing Fcomp (frequency of reference signal in the trigger) and h (hysteresis parameter). All simulations are done under HP-ADS software for 16-QAM modulation scheme.