PWM Ripple Removal with Sallen-Key or Analog Subtraction or Resistor-Capacitor

206

01:29:12

Standard RC filter compared to inverting cancellation filter and sallen-key with same resistors and capacitors. 1MHz switching.

Left side is a modified version of https://www.edn.com/cancel-pwm-dac-ripple-with-analog-subtraction/
Can use buffer and inverting buffer to eliminate delay in the inverted side.

Right side is a sallen-key filter
https://www.electronics-tutorials.ws/filter/sallen-key-filter.html

Bottom is simple RC filter

published 6 years ago

jpoulin0901

6 years ago

That's pretty cool. Anyone that has a roughly intermediate understanding of PWM signals (like me) can see why the first circuit has 2 sources and that they are complementary, but for illustrative purposes I think it would make sense to show them both operating on the same signal and producing different results. Which is to say I think you'd have done well to include an inverter explicitly. Just my opinion though. Cheers!

adamseamster

6 years ago

I agree

adamseamster

6 years ago

I made some changes, and added the Sallen-Key for more comparison

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