A/D Conversion With Imperfect Quantizers
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This paper analyzes mathematically the effect of quantizer threshold imperfection commonly encountered in the circuit implementation of analog-to-digltal (A/D) converters such as pulse code modulation (PCM) and sigma-delta () modulation. modulation, which is based on coarse quantization of oversampled (redundant) samples of a signal, enjoys a type of self-correction property for quantizer threshold errors (bias) that is not shared by PCM. Although "classical" modulation is inferior to PCM in the rate-distortion sense, this robustness feature is believed to be one of the reasons why modulation is preferred over PCM in A/D converters with imperfect quantizers. Motivated by these facts, other encoders are constructed in this paper that use redundancy to obtain a similar self-correction property, but that achieve higher order accuracy relative to bit rate compared to classical . More precisely, two different types of encoders are introduced that exhibit exponential accuracy in the bit rate (in contrast to the polynomial-type accuracy of classical ) while possessing the self-correction property. 2006 IEEE.
