Digital Signal Processing


A Segmented DAC based Sigma-Delta ADC by Employing DWA

Authors: Sakineh Jahangirzadeh, Ebrahim Farshidiy

Data weighted averaging algorithm work well for relatively low quantization levels , it begin to present significant problems when internal quantization levels are extended farther. Each additional bit of internal quantization causes an exponential increase in the complexity, size, and power dissipation of the DWA logic and DAC. This is because DWA algorithms work with unit-element DACs. The DAC must have 2N - 1 elements (where N is the number of bits of internal quantization), and the DWA logic must deal with the control signals feeding those 2N-1 unit elements. This paper discusses the prospect of using a segmented feedback path with coarse and ne signals to reduce DWA complexity for modulators with large internal quantizers. However, it also creates additional problems. mathematical analysis of the problems involved with segmenting the digital word in a P- ADC feedback path are presented, along with a potential solution that uses frequency-shapes this mismatch error. A potential circuit design for the frequency-shaping method is presented in detail. Mathematical analysis and behavioral simulation results are presented.

Comments: 10 Pages.

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Submission history

[v1] 2015-04-14 07:11:26

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