Opamp + digital potentiometer = no zero issue

Hi, I have a guitar pedal buffer/splitter circuit. This is controlled by hi-V digital potentiometers (AD5290). My problem is that these cannot go to zero ohms because the wiper resistance somewhere between 500-800 ohms. This means I cannot turn a channel all the way down. And there's a slight audible signal in my breadboard setup. Running a freq-domain simulation shows that minimum is -32dB. Any idea for an opamp configuration to get around this issue?

by Kraghen
November 02, 2021

The AD5290 supports a -V1 to +V2 output given the position of the wiper, right? Have you tried to supply a small negative lower voltage so that when the wiper is at the zero (minimum) position, the output becomes zero? Or in the negative that you will later stops (filter out) ?

by vanderghast
November 05, 2021

Alternatively, have you asked to Analog Devices how to solve that problem with a single power supply (0 to +Vcc) ?

by vanderghast
November 05, 2021
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