Op Amps for Everyone, 3rd Edition

Chapter 7. Development of the Nonideal Op Amp Equations

Ron Mancini

7.1. Introduction

Error sources in op amps are of two types, and they fall under the general classification of DC and AC errors. Examples of DC errors are input offset voltage and input bias current. The DC errors stay constant over the usable op amp frequency range; therefore the input bias current is 10 pA at 1 kHz and 10 pA at 10 kHz. Because of their constant and controlled behavior, DC errors are not considered until later chapters.

AC errors are flighty, so we address them here by developing a set of nonideal equations that account for AC errors. The AC errors may show up under DC conditions, but they get worse as the operating frequency increases. A good example of an AC error ...