[sdiy] Linear response VCOs?

[Mike Bryant]

This is why you use PDM, not PWM.  The pulses are at much higher frequency and easier to filter to the correct DC level with less noise.

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From: Synth-diy <synth-diy-bounces at synth-diy.org> on behalf of brianw <brianw at audiobanshee.com>
Sent: 20 March 2026 08:22
To: synth-diy at synth-diy.org <synth-diy at synth-diy.org>
Subject: Re: [sdiy] Linear response VCOs?

The challenge with PWM is that changing a rail-to-rail square wave into a steady DC value requires a lot of filtering. That filter must remove the sharp rise and fall of the raw PWM output, and thus the DC output value cannot sharply rise or fall either. The problem gets worse if a single channel needs to feed multiple unrelated CV values through a mux+S&H. The slew rate is horrible.

Brian


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