LOW-FREQUENCY NOISE REMOVING METHOD AND RELATED CMOS SENSING CIRCUIT

摘要

PURPOSE: A method is provided to make it possible to effectively remove the low frequency noise even when the internal noise level is larger than the minimum level of the sensing objective signal. CONSTITUTION: An intentional offset value is set beforehand. The intentional offset value is larger than a sensing objective signal "sig". A measuring device is provided for measuring the intentional offset value to obtain a measured intentional offset value "a" representing the quantity of the intentional offset value, and also for measuring a sum of the sensing objective signal "sig" and the intentional offset value to obtain a measured signal value "b" representing a summation of the quantity of the sensing objective siganl and the quantity of the intentional offset value. A ratio (b/a) of the measured signal value to the measured intentional offset value is obtained. The obtained ratio is used as noise reducing data for reducing the noise involved in a sensor output.