Evaluation of Null Method for Operational Amplifier Short-Time Testing

This paper investigates the NULL method to apply for the mass production testing of the operational amplifier. The NULL method is widely used to measure the operational amplifier characteristics accurately at the laboratory level, but it takes relatively a long measurement time. Then, we have examined the operation of the NULL method circuit with simulations where the SPICE model provided by the vendor is used for the amplifier under test. Some experiments have been also performed to confirm the agreements to the simulation results. We have found that the proper selection of the compensation capacitor values in the NULL method circuit can lead to short-time and stable testing, which would yield its applicability to the mass production testing.