High efficiency power transmitter based on envelope delta-sigma modulation (EDSM)

A delta-sigma modulated Class-E power amplifier is proposed and experimentally developed for high-efficiency and linear applications. The essential idea is based on envelope delta-sigma modulation (EDSM), which combines the Kahn technique envelope elimination and restoration (EER) and the delta-sigma modulated amplifier concept. The EDSM scheme increases the efficiency of the circuit by digitizing the envelope of the signal instead of the original RF signal. In the proposed scheme, the digitized envelope is not filtered as in the Kahn technique; consequently the output signal linearity is not deteriorated by the amplifier nonlinearity. A band pass filter is used only at the output of the system after the Class-E power amplifier to restore the original signal envelope.