MEASURING CIRCUIT FOR OPERATIONAL AMPLIFIER AND ITS MEASURING METHOD

摘要

PROBLEM TO BE SOLVED: To provide a measuring circuit for an operational amplifier and its measuring method which can measure an amplification factor only by measuring one input voltage and the output voltage of an amplifying circuit using the operational amplifier. SOLUTION: The amplifying circuit is composed of the operational amplifiers and resistor R1 and R2 while having the resistor R1 connected between a voltage input terminal T3 and an output terminal T1 and the resistor R2 connected between output terminals T1 and T2. The drain and source of an MOSFET Q1 are connected across the resistor R2 and when a switching part 3 turns on the MOSFET Q1, the operational amplifier 11 operates as a buffer to output the voltage V3 of an uninverted input terminal from the output terminal T1. When the switching part 3 turns off the MOSFET Q1, the operational amplifier 11 operates as an amplifier and an amplification factor measurement part 2 measures the amplification factor from measured values of the input and output voltages V1 and V2 and a voltage V3 at this time.