Chapter 3 - Separating and Managing AC and DC Gain

Abstract

DC and AC gain concepts are discussed as an introduction to single-supply op amp circuit design. AC and DC coupled designs are developed, and then used as building blocks to op amp circuits that must simultaneously amplify AC and DC signals. These circuits are presented in a number of cases that are intended to cover any combination of gain and offset required by the system. These circuits are primarily used to change a transducer voltage from one pair of minimum and maximum values to those required by an analog-to-digital converter, which is often referenced to a high-precision voltage reference. The solutions to the cases ensure that a single op amp is all that is required to accomplish gain and level translation in all cases. A single schematic, board layout, and design utility are proposed that will handle all such translations for a truly universal solution.