An Improved Dual-Quantization Technique Combined With Noise Shaping for Multi-bit Continuous Time Delta- Sigma Modulators

The present article proposed a modified dual-quantization technique accompanied with a tree-structure mismatch noise shaper in order to remove mismatch errors associated with DAC elements in feedback path of delta-sigma modulators. Having applied the modified dual-quantization technique without using extra digital filters, quantization error was removed from the modulator’s output. Tree structure utilized in the feedback path made noise shaping resulting from mismatches between n-bit and single-bit DACs. Moreover, the proposed technique removed the remaining noise caused by mismatches among n-bit DAC elements from the baseband. Analyzing simulation results in MATLAB indicated a significant increase in SFDR and SNDR and a significant decrease in the modulator’s sensitivity to DAC-nonlinearity in the proposed structure in proportion to the traditional structure.

Keywords:

delta-sigma modulators , dual-quantization , tree-structure , digital-analog converter , calibration