| 摘要 |
PROBLEM TO BE SOLVED: To allow the m-bit A/D converter to improve the ratio of signal to quantization noise. SOLUTION: An analog input is given to a digital averaging means 15 via a non-inverter 12a, aΔΣmodulator 13a, and a decimation filter 14a on one hand, and fed to the digital averaging means 15 via an inverter 12b, aΔΣmodulator 13b, and a decimation filter 14b on the other hand. The digital averaging means 15 sums an output of the decimation filter 14a and an inverse of an output of the decimation filter 14b, divides the sum by 2 and outputs the result, that is, a mean value in m-bit. Since theΔΣmodulators 13a, 13b quantize respectively different inputs, no correlation is in existence in a quantization noise included in a digital signal outputted from the decimation filters 14a, 14b to the digital averaging means 15 and the effect of the quantization noise is suppressed.
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