| 摘要 |
PROBLEM TO BE SOLVED: To widen the utilization rate of an output level with less output gradations by taking out a quantization error generated by a specified local quantizer, adding the output of the filter for feedback of a specified transmission function for filtering the quantization error and quantizer input and inputting them to the local quantizer. SOLUTION: A subtractor 3 takes out the quantization error Vq generated by the local quantizer 2 for which values outputted to the input are the seven ways of -3N to 1N, 0 and +1N to +3N (N is a natural number) and the filter 4 for the feedback provided with the transmission function indicated by an expression (1-z<-1> )<3> Vq/(1-z<-1> +0.5z<-2> )-1 filters the quantization error. An adder 1 adds the output of the filter 4 for the feedback and the input X of this quantizer and inputs them to the local quantizer 2. Thus, a feedback amount in a high band is made less than a normal third-orderΔΣmodulator, the stability of a system is enhanced, and an inputtable level is taken up to±2.37, even while setting the output gradations to the seven values of -3N to +3N.
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