| 摘要 |
PURPOSE: To measure, correct and reduce the effect of noise generated from a digital circuit on an analog circuit in real time by detecting the noise using a plurality of voltage comparators operating with different phase. CONSTITUTION: A noise detection circuit 1 comprises voltage comparators 2a, 2b which are operated, respectively, byϕ1,ϕ2 in negative phase and receive an input voltage V1 at the time of auto-zero and a reference voltage V2 at the time of comparison. At first, the comparator 2a measures the voltage difference between V1 and V2 and then the comparator 2b measures the voltage difference with a time lag of one half period behind the comparator 2a before delivering outputs OUT1, OUT2 to a correction amount operating circuit. Consequently, the noise can be measured every one half period at high sampling rate. Based on the magnitude of noise, the correction amount operating circuit operates a correction amount which is then delivered to a correction circuit. The correction circuit weights the correction value depending on the noise detection sensitivity of an analog circuit thus correcting the output voltage therefrom.
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