Efficiency Enhancement in Delta-Sigma Modulator Based Transmitter Using Level Transformation

Abstract

This paper proposes a new architecture of delta-sigma modulator (DSM) based transmitter for addressing the key limitation of multi-level DSM. The performance of multi-level DSM deteriorates at the RF amplification stage due to increase in peak to average power ratio (PAPR) of quantized signal as the number of quantization level increases. In this paper, a level transformation stage is introduced after DSM which significantly improves the transmitter efficiency in comparison to multi-level DSM. This novel topology is validated using 3 to 2 level and 5 to 3 level signal transformation which possess the advantage of multilevel signal at DSM stage along with the benefit of low PAPR signal at amplification stage. The implementation result shows that coding efficiency is improved by 5.6% in 3to2 level and 14.3% in 5to3 level signal transformation in comparison to 2 level and 3 level DSM based transmitter respectively.