Power efficient linear transmitters using sigma-delta modulation with switching amplifiers

Authors: TAYFUN NESIMOGLU

Abstract: In conventional envelope elimination and restoration transmitters, the envelope information of the carrier is reconstructed by modulating the supply voltage of the switching amplifier. In this paper, it is shown that the supply voltage modulation introduces nonlinearity and reduces the average power efficiency of the transmitter. Here, novel transmitter architectures using sigma-delta--modulated carrier signals are proposed to overcome these shortcomings. The proposed architecture's and conventional envelope elimination and restoration transmitter's linearity and efficiency performances are compared at various oversampling rates and signal bandwidths. It is demonstrated that the proposed architectures may provide better linearity and efficiency than conventional envelope elimination and restoration transmitters.

Keywords: Envelope elimination and restoration, power amplifier, switching amplifier, nonlinear distortion, intermodulation distortion, sigma-delta modulation, transmitter design

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