| 摘要 |
A noise shaper includes an incomplete integrator which conducts an addition of a present data and a last sampled data stored and a positive coefficient smaller than 1, a complete integrator which conducts an addition of a storage data before one sample delay and a present data, a three-value quantizing circuit which outputs 0, +1 or -1 signal as an output signal, and a feedback circuit which feeds-back the output signal from the three-value quantizing circuit to the incomplete integrator and the complete integrator. The noise shaper may further include a delay-data supply selection circuit which supplies the last sampled data stored and the positive coefficient to the incomplete integrator only when the output signal supplied from the three-value quantizing circuit through the feed-back circuit is zero. The output signal from the noise shaper can be made zero without deteriorating signal to noise (S/N) ratio when no input signal is inputted to the noise shaper.
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