Jada: Just another discrete amp:

stinius · 27th August 2009, 10:04 PM

Hi

This is the simulations of my class d design.

Does it look ok?

Cheers
Stinius

darkfenriz · 28th August 2009, 08:24 AM

Where's the ripple?

stinius · 28th August 2009, 05:35 PM

Quote:

Originally Posted by darkfenriz

Where's the ripple?

Hi darkfenriz
This is not a UCD amp, so I don’t 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

darkfenriz · 28th August 2009, 07:16 PM

So what's the switching frequency and output filter?
Is that a clocked design with multiple LC resonant traps?

stinius · 28th August 2009, 08:08 PM

Quote:

Originally Posted by darkfenriz

So what's the switching frequency and output filter?
Is that a clocked design with multiple LC resonant traps?

It’s a self oscillating design, so as you know the switching frequency is not fixed, but it never drops down to a scary frequency.

It’s 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

J.R.Freeman · 28th August 2009, 10:14 PM

Quote:

Originally Posted by stinius

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

darkfenriz · 29th August 2009, 10:23 AM

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

stinius · 29th August 2009, 05:24 PM

Hi

JRF
Thank you.

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

I didn’t know about the frequency limitation in Orcad Pspice, I will have to ask syn08 about that.

The frontend I’m using is this one: Return of my differential VAS

I’m not using any global feedback, but of course some feedback in the frontend and also in the Class D buffer.
I’m still working on the circuit so I don’t want to reveal too much before I’m sure that it’s a working concept.

Cheers (Mvh)

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28th August 2009, 08:24 AM	#2
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	Where's the ripple?

28th August 2009, 07:16 PM	#4
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	So what's the switching frequency and output filter? Is that a clocked design with multiple LC resonant traps?

29th August 2009, 10:23 AM	#7
darkfenriz diyAudio Member Join Date: Jun 2004 Location: Warsaw	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

29th August 2009, 05:24 PM	#8
stinius diyAudio Member Join Date: Oct 2008	Hi JRF Thank you. df I know there are some limitations in simulation compared to real circuits; this is a new concept so I’m using the simulator to check if the concept looks interesting, and I think it does. I’m not that concerned about the THD right now, but in the simulation I’m now down in the E-4 range. I didn’t know about the frequency limitation in Orcad Pspice, I will have to ask syn08 about that. The frontend I’m using is this one: Return of my differential VAS I’m not using any global feedback, but of course some feedback in the frontend and also in the Class D buffer. I’m still working on the circuit so I don’t want to reveal too much before I’m sure that it’s a working concept. Cheers (Mvh)

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