| 摘要 |
<p>An input signal is quantized by a quantizer after being passed through plural loop filters. A last-stage loop filter is formed of an operational amplifier for generating an output signal, a sampling capacitor for sampling the input signal, an integrating capacitor for integrating the signal sampled by the capacitor and plural switches for switching over signal paths. A control circuit controls on/off states of the switches to discharge the sampling capacitor and the integrating capacitor and causes the loop filter to repeat a sampling operation and an integrating operation plural times. The control circuit lastly connects the sampling capacitor and the integrating capacitor to a state, which is opposite to the state of the integrating operation time and turns on a converting switch so that the A/D converter A/D-converts the output signal of the loop filter.</p> |
