| 摘要 |
PROBLEM TO BE SOLVED: To provide an amplifier circuit capable of reducing drift of an input offset voltage using a chopper amplifier circuit and capable of shortening the time required for recovery from a state where negative feed back control is stopped working normally by influences an excessive input signal or the like, to a normal state.SOLUTION: If an input offset voltage of a main amplifier circuit 5 is out of a predetermined range, a holding operation of an output voltage Vb of a low-pass filter 20 in a sample/hold circuit 30 is stopped, and the output voltage Vb of the low-pass filter 20 is directly outputted to a correction signal supply circuit G3. Thus, for example, if a state where negative feedback control is temporarily stopped working by influences of an excessive input voltage Vin to the main amplifier circuit 5 occurs and the input offset voltage of the main amplifier circuit 5 is out of the predetermined range, no response delay is generated by the holding operation of the sample/hold circuit 30 and a response speed of an offset correction circuit 6 is accelerated.SELECTED DRAWING: Figure 1 |
