Justification for the need for high voltage/power Class D amplifiers

One application is high power pro audio gear. Once you get into the 1kW+ range it starts making better sense.

It won't.

There is little correlation between physical size and method. In fact, Class D usually requires more complicated circuitry to obtain decent performance.

There aren't any compelling reasons for class D. Its just another method that had advantages in some situations, and disadvantages in others. Class D wont replace the other methods it is used in addition to the other methods.

If your doing a study your supposed to identify the disadvantages as well as the advantages. You seem to be assuming the Class D is god's gift to amplifiers from the outset. It isn't.

Kevin Aylward snipped-for-privacy@anasoft.co.uk

Matthew,

The efficiency is better but a close second is crossover distortion. True Class D has no cross over distortion also the design is more simple over the temperature range because one fet is switched full on or off.

Ray

Off hand it smacks of homework. They're probably also indoctrinating 'em that digital will always replace analogue and that nothing worthy is designed below 10GHz and that microsoft is the best thing since sliced bread. regards john

Matthew, Correction to my post. The other advantage to a switcher vs AB is the voltage rating of the switch and size of the out put transformer along with the power loss due to the bias current in the output transformer. a very good pwm can be made with two 555s and one IR2111. driving two totempole N fets.

Ray

Good article in EDN, Nov 11, 2004 called "Getting the most from Class D multichannel audio amplifiers". Mentions one aspect that I had not considered about class D... they have *no* power supply rejection at all! Whatever trash comes through the supply, comes out the output because all these amps do is switch the supply off and on.

I guess there are still a few legs (ie feedback) left to linear circuits after all.

Best regards,

Bob Masta dqatechATdaqartaDOTcom D A Q A R T A Data AcQuisition And Real-Time Analysis

This was made clear to me when I built a Class 'D' amp for a signal with a constant amplitude of 121.6 Volts P/P and which had to degrade linearly down to