Class-G Amp

195

01:32:21

This is a class-G amp. It is usually described as a class-A amp with variable voltage rails to increase the efficiency. As far as I can tell, this is a class-AB amp with variable voltage rails. Basically, when the voltage of the signal gets high enough, it switches from the 15V power supply to the 30V power supply. Once the input gets to 30V, it switches to the 45V power supply. When it starts going down again, it switches back to the 30V power supply, and then the 15V one, etc. This way, the output signal never gets below 15V lower then the power supply, making it much more efficient than it would normally be, if it had a constant 45V power supply. I tried measuring the efficiency the best I could, and got 80-85%, which is considerably higher than the maximum theoretical efficiency of 78.5% for a Class-AB amp. Often, class-AB amps are around 60% efficiency, which means this amp will dissipate half as much heat than the 60% efficient class-AB amp.

published 8 years ago

hurz

8 years ago

Yes, and whats happend now? Are you writing a good description for the community to help others to understand how and why this principe works? Or do you change it to a private object, cuz its for 99.9% of user here on EC useless without a good explanation!

jason9

8 years ago

I'll write a description now, I just didn't really know for sure if it was a class-H amp.

hurz

8 years ago

And remove one voltage level stage. Its not needed to understand the principle.

jason9

8 years ago

This isn't just for educational purpose, it's also to be a good, efficient amp.

jason9

8 years ago

Could this actually be class-G and not class-H?

hurz

8 years ago

It isn't JUST educational? Are you kidding?

jason9

8 years ago

I'm not quite sure what you're trying to say, but I'm not making this stuff mainly to teach other people, but because it's fun to make it, and also to try to make it efficient. If it's sole purpose was for education, then I would have made only two different supplies, not three, but I want to make it efficient because it's fun to do that and more sensible.

hurz

8 years ago

And what is the fun for us? Watching a messy circuit? For you it was fun to make it, right. Thats fine and this is the best way to learn or even the motivation. Thats fine, but why publish it, because you expect we also have fun?

jason9

8 years ago

Actually, I just publish every circuit I make, and if someone doesn't care for my circuits, then it's not like they're forced to look at them.

hurz

8 years ago

Make=simulate , look= 😵👎 you do not say anything about YOUR motivation

jason9

8 years ago

I don't get what you're trying to say.

glassdance

8 years ago

He says why publish not just save I do believe... What motivation do have for publication

jason9

8 years ago

Thanks, @glassdance. @hurz, I wanted to publish this circuit in particular because there weren't any class-H/class-G amps around.

hurz

8 years ago

Keep it simple. Things getting complex, to end of project anyway.

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