When designing a class D amplifier, is it better to use a PWM modulator, or the DSD/PDM signal right from the modulator? Or does it really depend on the design?
Back in 2008 or so I was playing with 555 timers and PWM stuff.
It was a PITA to use them and I wanted something better........................
So, I built a True PWM modulator out of a Dual opamp and it worked like a charm, then later I moved on to using fast comparator's and TTL and such to drive some 1200uh coil I had handwound and found I could make a rippleless super clean 0v to 5v voltage level with it on the output of the coil with just a 7404 as a driver.
I was using about a 200Khz to 1-2 MHz clock inputs on it and was able to produce some very clean amplified sine waves up to +100khz on the output of the thing, I was quite impressed with what I saw on the scope but never did anything with it since.
I still have the original protoboards from those days, gonna get them out again some time soon.
This was way before we even had the ability to do realtime RTA /FFT (ie~THD) measurements. 😉
Cheers !! 🙂
jer 🙂
It was a PITA to use them and I wanted something better........................
So, I built a True PWM modulator out of a Dual opamp and it worked like a charm, then later I moved on to using fast comparator's and TTL and such to drive some 1200uh coil I had handwound and found I could make a rippleless super clean 0v to 5v voltage level with it on the output of the coil with just a 7404 as a driver.
I was using about a 200Khz to 1-2 MHz clock inputs on it and was able to produce some very clean amplified sine waves up to +100khz on the output of the thing, I was quite impressed with what I saw on the scope but never did anything with it since.
I still have the original protoboards from those days, gonna get them out again some time soon.
This was way before we even had the ability to do realtime RTA /FFT (ie~THD) measurements. 😉
Cheers !! 🙂
jer 🙂
I've been pretty much living at digikey and mouser looking at PWM modulator ICs lol
I just figured if you're getting a pulsed signal already from the modulator, you wouldn't need to have an audio signal to convert back into PWM at all. You could potentially knock off one step in the conversion chain, thus reducing the risk of adding any kind of distortion or audible artifacts. But I honestly don't know because I've also seen that those PWM modulators have other features on them that could potentially be beneficial in the design.