Ron Mancini
Texas Instruments

Amplifier selection is confusing because there are many different amplifier types to choose from and many of the amplifiers seem to do identical jobs. One sure thing about a semiconductor amplifier is it involves either internal or external feedback. The best method to control gain variations is with feedback, but there is no free lunch because along with feedback comes the possibility of overshoot, ringing, and eventually oscillation. Internal compensation is transparent to the user, and the amplifier is stable in the recommended application and conditions, but any amplifier with gains greater than one can oscillate under certain conditions. You must supply external compensation components for amplifiers requiring external feedback or they oscillate or saturate. Always investigate the compensation situation when selecting an amplifier because it is exasperating to complete a design only to discover that you built an oscillator rather than an amplifier.