PURPOSE: To prevent the deterioration of characteristics, by connecting a compensating switch to a switch connected with a capacitor having inverse element sensitivity as that of a filter consisting of a stray capacitance of the switch so that the stray capacitor can be connected in parallel with this capaitor.
CONSTITUTION: A compensating switch SWx is provided to a circuit consisting of switches SW1∼SW4, sampling capacitors CA4, CA5, intergrating capacitor CB2, and operational amplifier OP2. The switch SWx is the same constitution as the switches SW1∼SW4 and other switches, and it has a stray capacitor CSx, which is connected in parallel with the sampling capacitor CA5 via the switches SW3, 4 when the switches SW1∼SW4 and the SWx are in the state as shown in figure. Further, the stray capacitor CSx is connected in parallel with the sampling capacitor CA5, even when the switch SW1 is changed over to an operational amplifier OP1 side and the switch SW3 is changed over to an operational amplifier OP3. Thus, the deterioration of the characteristics can be suppressed by the compensating switch SWx.
UENO NORIO
TSUNOISHI MITSUO
KOBAYASHI KAZUHIRO
