Improving Coding Efficiency by compromising linearity in delta-sigma based transmitters

In this paper the Coding Efficiency in multi-bit delta-sigma based transmitters has been improved significantly by only adjusting the quantizer´s threshold values. To achieve this, the transmitter´s linearity should be compromised. Usually the space between thresholds in a quantizer of a multi-bit delta-sigma modulator is uniform which not the optimum choice is for Coding Efficiency. For an LTE signal with 3.84 MHz bandwidth and 16 times oversampling, the Coding Efficiency improves from 11.3% to 23.9% and from 31.2% to 48.7% by only changing the quantizer´s threshold values in a 3-level and a 5-level multi-bit delta-sigma modulators respectively. However, their Signal to Noise and Distortion Ratios degrade from 45.1 dB to 35.0 dB and from 51 dB to 42 dB respectively.