Ten Essential Skills for Electrical Engineers

6

HOW TO WORK WITH OP-AMP CIRCUITS

Operational amplifiers, or op-amps, satisfy many analog signal processing tasks including amplifying, level-shifting, and filtering. Op-amps are a workhorse of analog design below 1 MHz and are often used at higher frequencies. Knowing how to design basic op-amp circuits and knowing how to work with practical or nonideal op-amps are prime interview topics and key skills for entry-level engineers.

The op-amp has been used since the mid 1940s and is an excellent example of simplicity and cleverness; simple because it is just a high-gain differential amplifier and clever because of the many useful functions that can be implemented by surrounding it with a few external parts. In the 1950s, the author’s father built op-amp circuits about the size of a brick using vacuum tubes. Later, he built op-amps out of handfuls of discrete transistors and he certainly appreciated the arrival of integrated circuit op-amps in the 1960s. Today’s op-amps are small integrated circuits that use minimal power and can be purchased for less than a dollar. As op-amps continue to improve, they will satisfy an ever-increasing number of design applications, and one day as you look back at the improvements in op-amps in your career you’ll probably be as impressed as the author’s father.

As a circuit designer you’ll certainly appreciate that when you properly design an op-amp circuit it will likely work as expected and require minimal troubleshooting. As your career progresses, ...