This article describes the concept of a versatile programmable amplifier using digital potentiometers with nonvolatile memory. By replacing mechanical potentiometers, the AD523x series of digital potentiometers mentioned in this article can improve the resolution and stability of the adjustment circuit.
This document describes circuits that use the AD523x family of digital potentiometers with nonvolatile memory to create programmable amplifiers and attenuators. These circuits address limitations of mechanical potentiometers, such as limited resolution, poor temperature coefficients, and resistance drift over time. The text details a basic inverting configuration and a bipolar programmable-gain amplifier with linear step adjustment.
The circuit can yield a temperature coefficient as low as 35 ppm/°C if using the AD5235.
The wiper resistance is typically between 50 Ω and 100 Ω.
Discrete resistors must be added in series with the potentiometers to comply with the voltage limitation.