Abstract: This application brief describes how to control analog phase shift digitally using a combination of digital potentiometers and standard operational amplifiers (op amps). It is intended to serve as a design example for engineers needing to implement digital phase shift in a circuitry with no specific application. It presents common op amp phase shift configurations and how to implement them using a digital potentiometer in place of mechanical potentiometers or fixed resistors. Formulas for calculating phase shift are included in the application note. Application Note 184 Digitally-Controlled Phase Shift Using the DS1669 www.maxim-ic.com CONTROLLING PHASE SHIFT DIGITALLY Altering the phase response of a signal without changing its amplitude characteristics is commonly performed using an allpass filter, as in Figure 1. The response of this circuit is given by A simple phase shift circuit can be implemented using an allpass filter. Figure 1 As the signal frequency varies from DC to infinity, the phase shift will vary from 0 to +180 degrees. You can also see that by varying R1, the phase shift at a given frequ……