Programmable Wien-Bridge Oscillator Using Digital Potentiometers

Overview

This application note describes the implementation of a diode-stabilized Wien-bridge oscillator that utilizes digital potentiometers for programmable control. The design uses the Analog Devices AD5232 dual digital potentiometer to set the oscillation frequency and the AD5231 to adjust the output amplitude independently. By varying the resistance values, the circuit can generate accurate sine waves ranging from 10 kHz to 200 kHz. The document provides technical analysis of the loop gain, phase shift requirements for oscillation, and the mathematical formulas for calculating frequency based on resistance codes. It also discusses practical considerations such as bandwidth limitations of digital potentiometers and methods for ensuring simultaneous resistance updates to avoid intermediate state errors.

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