SEMICONDUCTOR INTEGRATED CIRCUIT DEVICE

摘要

PROBLEM TO BE SOLVED: To highly accurately A/D convert an AC component of an input voltage by including a removal function for removing sampling capacitance and a DC component of an input signal. SOLUTION: A primary delta-sigma modulation circuit 1 samples an input voltage VIN under a clock signalϕ1, performs charge transfer to an electrostatic capacitor Cs under a clock signalϕ2, and performs voltage integrating operation. Under the clock signalϕ2, a charge component corresponding to a DC offset voltage of the input voltage VIN is subtracted from the amount of charges to be transferred to an electrostatic capacitor Cs0, thereby removing the DC component. Actually, under the clock signalϕ2, input-side switches S1-0 to S1-2n-1 of divided electrostatic capacitors Csd0-Csd2n-1 are changed over to either a high voltage reference voltage VT1 or a low voltage reference voltage VB1, thereby regulating the amount of charges to be transferred to the electrostatic capacitor Cs0. COPYRIGHT: (C)2008,JPO&INPIT