What Makes Op Amp Testing So Challenging

Operational amplifiers are a key building block used by engineers to develop analog circuits and are thus one of the most widely used electronic devices today. Unfortunately these little workhorses have a propensity to oscillate and their testing entails minute measurement, which means that one has to get creative in order to produce accurate results. The staff at ACT has significant expertise dealing with analog phenomena and, over the last year, has developed a variety of field proven methods:

• By their very nature, op amps (which are differential amplifiers) have very high gain and tend to oscillate. Because of this they must be stabilized before precise measurements can be taken. ACT has perfected compensation techniques that operate into the hundreds of MHz range.
• When input bias currents are small (as is the case with most newer op amps) additional complications arise. Small currents are tested with large precision resistors, making the circuitry far more susceptible to noise and stray EM fields. ACT addresses this issue through guard banding, Faraday shielding, and/or battery powering circuitry.
• Low noise op amps present another challenge. When noise measurements are required on these: low-noise, battery-powered, shielded fixtures are a must.

Given all these challenges, competency with analog technology should really be considered a mandatory requirement for any test house performing op amp testing. ACT has the experience as well as the fixturization to successfully evaluate op amps.