Author Topic: Cancelling ripple in your PWM DAC  (Read 919 times)

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Offline DabbotTopic starter

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Cancelling ripple in your PWM DAC
« on: August 25, 2019, 04:28:06 am »
I just tried https://www.edn.com/design/analog/4459116/Cancel-PWM-DAC-ripple-with-analog-subtraction and I have to say it works remarkably well.

The example on the site includes an external inverter, but I programmed a PIC to generate a complementary 31KHz PWM signal, then sent each output into the RC filter network as seen on the site. 10Kohm resistors and 0.1uf capacitors. Pretty good result for one extra micro pin and two extra passive components.

It buries the ripple into the noise as far as I can tell using my scope (noisy environment). The only downside that I can see is the increased time for the output to settle, which can be addressed in software, but isn't a problem for my intents and purposes.

Has anyone else taken this approach?

 
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