MHz amplifier

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I was a little bit bored today so i started playing with a LM311P and a TC4422, this was the outcome after a few hours of playing around:

MHzD-Amp.jpg

outputwaveform.jpg

Video.
 
The amp sound reather good, i don´t have a speaker that would make the actual sound justice, so i need to get RMAA and install a M-Audio Audiophile USB soundcard on the laptop to get a line in, since the laptop soundcard doesent have one.

I also need to find my T106-2 cores to replace this crappy -26 material one.
 
My amp is ****, i tried to measure it but IMD + Noise peaked @ over 24000%, however thd was only 0.06%.

The imd problem could be due to that the amp generates a tone on low freqs, yet im not sure if it comes from the preamp or the poweramp, or if its due to that i dont have af error feedback yet.
 
The measurement errors turned out to be an unknown mic boost on the line input, the beeping coming from the amp on low freqs turned out to be the signal generator because it was also hearable in the laptop speakers.

Anyways i built a stereo version of my little amp today, pics are here.
 
Lum, that have to do with that the LM311P output is inverting, if i use a TC4421, then the inputs would be the same as fumac´s block diagram.

Bender.ru, the higher switching frequency allows for more accurate reproduction of higher part of the audio band, class-d.net explains this.
 
lumanauw

is this also applicable to self-oscillating classD? Isn't that in selfoscillating, it's self-adjusting towards errors?

You are correct to some degree. Saying that a higher frequency improves the high frequency reproduction needs to be proven, not just taken for a theoretical to practical translation.

Self oscillating amplifiers gets more loop gain the more it attenuates the switching ripple but at some point the propagation delay and switching nonlinearities will take over and cause more distortion. My experience is that going above 600kHz is difficult without generating very high levels of radiated emissions. Of course if one is only building for DIY it would be OK as long as the neighbours pace maker does not stop.

Saying that EMI decreases when the switching frequency is pushed above 1MHz is pure fantasy and based only on the assumption that if the residual decreases in amplitude the EMI decreases. If you switch twice as many times the radiated emissions double and if you want to use this higher frequency for improving the sound the DV/DT need to be shortened easily doubling the radiated noise again.
 
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