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Class D Switching Power Amplifiers and Power D/A conversion

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Old 27th August 2009, 10:04 PM   #1
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Default Jada: Just another discrete amp:

Hi

This is the simulations of my class d design.

Does it look ok?

Cheers
Stinius
Attached Files
File Type: pdf THD 1k 67% pwr.pdf (7.9 KB, 97 views)
File Type: pdf Transient 1k.pdf (53.4 KB, 47 views)
File Type: pdf Transient 10k.pdf (24.6 KB, 44 views)
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Old 28th August 2009, 08:24 AM   #2
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Where's the ripple?
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Old 28th August 2009, 05:35 PM   #3
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Quote:
Originally Posted by darkfenriz View Post
Where's the ripple?
Hi darkfenriz
This is not a UCD amp, so I donít need the ripple.
You will see some ripple if you look closer and of course at lower output the ripple will be easier to see.

Cheers
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Old 28th August 2009, 07:16 PM   #4
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So what's the switching frequency and output filter?
Is that a clocked design with multiple LC resonant traps?
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Old 28th August 2009, 08:08 PM   #5
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Originally Posted by darkfenriz View Post
So what's the switching frequency and output filter?
Is that a clocked design with multiple LC resonant traps?
Itís a self oscillating design, so as you know the switching frequency is not fixed, but it never drops down to a scary frequency.

Itís not a UCD, but more like an analogue frontend with a Class D buffer.

Yes the output filter is more than just an L and C.

Cheers
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Old 28th August 2009, 10:14 PM   #6
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Quote:
Originally Posted by stinius View Post
Hi

This is the simulations of my class d design.

Does it look ok?

Cheers
Stinius
'THD numbers look impressive! That's neat - I use OrCAD 16 at work. Keep us updated on your project, and good luck.

JRF
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Old 29th August 2009, 10:23 AM   #7
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You've still provided very little information.
I can only suspect you've chosen a very high carrier frequency that allows a lot of feedback. Harmonics reveil that.
Simulate 3+7kHz IMD and check the distortion products in the range of 10-21kHz, is the number still looking so nice as 5E-3% ? I bet it doesn't.
Also if your switching frequency gets higher than some 200-300 kHz, then use simulation only for proof of concept, not for THD estimation (useless).

Mvh
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Old 29th August 2009, 05:24 PM   #8
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Hi

JRF
Thank you.

df
I know there are some limitations in simulation compared to real circuits; this is a new concept so Iím using the simulator to check if the concept looks interesting, and I think it does. Iím not that concerned about the THD right now, but in the simulation Iím now down in the E-4 range.

I didnít know about the frequency limitation in Orcad Pspice, I will have to ask syn08 about that.

The frontend Iím using is this one: Return of my differential VAS

Iím not using any global feedback, but of course some feedback in the frontend and also in the Class D buffer.
Iím still working on the circuit so I donít want to reveal too much before Iím sure that itís a working concept.

Cheers (Mvh)
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