| 摘要 |
PURPOSE:To compensate offset automatically by applying an integral voltage, which is changed to the negative and the positive with a large time constant, for positive and negative fluctuation of the output voltage obtained by applying a fixed processing to an input voltage. CONSTITUTION:Input voltage Vin is received, and binary output signal Vout indicating magnitude for set voltage Vs is input to offset compensating circuit 21. Circuit 21 consists of bipolar voltage circuit 22, integrating circuit 23, and voltage dividing circuit 24, and circuit 22 outputs voltage + or -Vr according to voltage Vout in syncronization with clock signal CL, and sample hold capacitor C1 is charged through contact S2 of switch SW of circuit 23, and next, integrating capacitor C2 is discharged through contact S2. Circuit 23 constitutes a switched capacitor type integrating circuit, and the capacity value is extended due to operational amplifier OP, and the equivalent time constant is determined by C2/C1 and can be large sufficiently. DC components of the output of circuit 23 are divided in 24 and are fed back negatively to operational amplifier 13, thereby compensating offset automatically. |
