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Old 10th July 2013, 06:07 PM   #191
ChrisA is offline ChrisA  United States
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Quote:
Originally Posted by hochopeper View Post
Confirming my understanding of the AD7986 sample clock timing requirements:
For best accuracy you get better results if yu think of the clock as an analog signal. After all, it really is just volts in a wire. Now you can apply what you know about noise to a clock. Don't think of "jitter" that is a time domain concept that is a result of noise. Work on the root causes which are various types of noise.

When you are dealing with MHz level clocks, what you have is radio frequency (RF) signals and you can aply RF techniques that have MUCH lower noise then flip-flops and the like. Thinks about frequency dividers, mixers and filters.
noise is measured in units of db/Hz

Any clock is going to have amplitude the phase error and all kinds of harmonic distortions just like any other signal. The finally when you convert it to a square wave these errors show up a "jitter" and BTW "jitter" will have a distribution, a mean and a sigma on it. Just thing abot what a 120Hz ripple will do to the clock it will inter mod withthe 1MHz clock. "thinking digital" will never uncover stuff like that.

The trick is to have a very clean, low phase noise sine wave of the correct frequency and then "square it". You are not going to get to "picoseconds" by "thinking digital" it blinds you to all the real problems
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Old 13th July 2013, 06:07 PM   #192
RNMarsh is offline RNMarsh  United States
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What a great answere.

-RNM
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Old 15th July 2013, 06:30 AM   #193
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@chrisA:

Hi ... an interesting way of looking at it I think ... might you have a link to an article or something else that in "technical layman words" describe how this can be done in practice?

Greetings,

Jesper
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Last edited by gentlevoice; 15th July 2013 at 06:33 AM.
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Old 28th August 2013, 07:18 PM   #194
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Default Status of your Audio ADC, the schematic...

Did you complete your Audio ADC? Are PCB's available? Please update the status.
Take care and great work.
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Old 29th August 2013, 05:51 AM   #195
RNMarsh is offline RNMarsh  United States
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Do you have any spec measured data on your ADC?? Especially interested in accuracy below -100db re 1v.

-RNM
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Old 30th August 2013, 03:04 PM   #196
Frex is offline Frex  France
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Hello mrsavage and RNMarsh,

I'm not sure about who you are talk on your previous post...
I'm the author of this thread, and if you speak about it
i will answer with great pleasure, but i'm little confusing
because some others previous post speak also about ADC....
Could you be more precise from what you are talking about ?
Thank you.

Frex
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Old 30th August 2013, 07:08 PM   #197
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Default See Post Number 3 of this thread

See Post Num ber 3 of this thread. If you didn't do this PCB, then who did.
Point us to the correct person. Thanks and sorry for the mixup.
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Old 30th August 2013, 07:42 PM   #198
1audio is offline 1audio  United States
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It seems the schematic and layout are not there anymore. Repost?

I would really like an AK5394A ADC (I have the demo board but something with more flexible input conditioning would be nice).
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Old 31st August 2013, 08:26 AM   #199
Frex is offline Frex  France
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Hello,

So, you speak about the AA5381v1 ADC that i have built.
I can provide bare PCB of this design, as my others projects (few one in stock).
Regards

Frex
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Old 3rd September 2013, 08:24 PM   #200
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Default Yes, that's the one!

Yes, that's the one! If I could obtain a couple of these PCB's that would be great.
You stated that after you built the PCB it did not measure up to your specs?
Explain and post your analysis, maybe we can improve on the design, or the
layout has a problem. Other threads have stated that doing these types of
PCB's is difficult because is critical for proper operation. Providing feedback
and suggestions is what DIYAUDIO.COM is all about. Take care.
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