Probability distribution function of crossover frequency of operational amplifiers

TL;DR

This paper experimentally studies the probability distribution of crossover frequency in ADA4898-2 operational amplifiers using a novel, accurate, and fast measurement method based on a USB Lock-In amplifier.

Contribution

It introduces a new experimental approach to measure the crossover frequency distribution of operational amplifiers with improved accuracy and speed.

Findings

Measured crossover frequency distribution of 200 samples

Demonstrated the effectiveness of the USB Lock-In amplifier method

Validated the universal relation between output and input voltages at relevant frequencies

Abstract

For the first time the cumulative distribution function of the crossover frequency of a contemporary operational amplifier ADA4898-2 is experimentally studied. Using a USB Lock-In amplifier, which allows automatic frequency sweep of the current response of a non-inverting amplifier with significant static amplification, we measure the crossover frequency of 200 samples of ADA4898-2 operational amplifiers. This new method gives a significant advantage in accuracy and speed of study of every operational amplifier. The theory we use is based on the universal relation between time dependent output and input voltages. This common relation for all operational amplifiers is applicable for frequencies much smaller than the crossover frequency and the frequencies of non-dominant poles. In other words, this approximation is adequate, when an operational amplifier is included in a circuit with significant amplification.