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Class D Switching Power Amplifiers and Power D/A conversion

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Old 6th February 2007, 08:41 AM   #1
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Default Really Nutty Class D (RNCD)

Here I present something to make all of the class D amplifier people turn green.

Those engineer types will see what's going on here. If you don't get how this thing works, ask and I'll come back with a reply. It's pretty simple though.

Click the image to open in full size.


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Old 6th February 2007, 04:38 PM   #2
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Wow, one more NCD?
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Best regards,
E1.
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Old 6th February 2007, 07:11 PM   #3
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I can't believe I indicated a P-channel in the diagram.

For the record, it is N-channel.
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Old 6th February 2007, 08:37 PM   #4
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what's the diode for?
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Old 6th February 2007, 09:03 PM   #5
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The diode rectifies the output of the switching driver. If it was not there, the device would be trying to switch 10V at 60KHz into the cap and load.... Not good. (This is a switching amplifier, not linear.)
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Old 6th February 2007, 09:07 PM   #6
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So if I understand correctly you've built a VCO and output diode works as a FM-discriminator, is it right?
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Old 6th February 2007, 09:10 PM   #7
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No.

This works on duty cycle.

The average amount of power in the inductor is controlled by pulse width, and to some extent, frequency.
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Old 6th February 2007, 09:37 PM   #8
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OK, I think I got it...
You called it classD/A because it is both PWM and ineffifient?
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Old 7th February 2007, 12:12 AM   #9
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Well, it's probably about twice as efficient as a typical class A of the same topology.

What you see here is a class D stage acting as the upper transistor of the class A stage.

The resistor acts as the class A stage's load in order to pull down and do the other half of the wave.
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Old 7th February 2007, 12:48 PM   #10
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I have 3 questions......

1) Can I mod this with better input caps?

2) What kind of speaker cable should I use?

3) Can you recommend me a power supply?

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