Eval Board with SAR ADC

>> If you're concerned about delay in conversion, why not consider flash
>> converters?
>
>Find a flash converter with more then 12 bits of resolution.
>
>> I don't know of a lot of successive-approximation converters
>> still in use.
>
>Most of MHz class sampling A/Ds are charge redistribution SARs.
>
>> And if you're using it for audio processing, why do you care so much
>> about delay?
>
>There are applications like adaptive noise canceling where processing
delay 
>is crucial.
>
>> Randy Yates
>
>Lamer.

Thanks Vladimir "Lamer" Vassilevsky. That are the points.
And that's why I expected that there should be such a device somewhere.

Some audio processing algorithms need low delay and high resolution.
The algorithm that I would like to implement could be implemented in such a
way, that it processes sample by sample.

T. 

>
>"Randy Yates" <yates@digitalsignallabs.com> wrote in message 
>news:874nmor0n3.fsf@randy.site...
>> "Thomas6666" <61878@dsprelated> writes:
>>
>>> it's been a while ago since someone asked here for an DSP eval board
(for
>>> audio processing) that's got a SAR analog-digital converter.
>>> Theoretical it should be possible to reach very low delay between an 
>>> audio
>>> input and the output after processing by a DSP.
>>> Does anyone know a device with a fast SAR ADC (that could be used for 
>>> audio
>>> processing)? A board with suiting anti-aliasing filters, floating point

>>> DSP
>>> and fast DAC would be perfect.
>>> Have you got an idea, what the minimum expected delay could be?
>
>> If you're concerned about delay in conversion, why not consider flash
>> converters?
>
>Find a flash converter with more then 12 bits of resolution.

Flash converters have mostly given way to several flavours of pipelined
converters, which break the high resolution problem down into a number of
coarser resolution steps.

>> I don't know of a lot of successive-approximation converters
>> still in use.
>
>Most of MHz class sampling A/Ds are charge redistribution SARs.

Yep, SAR is still *the* mainstream technique for conversion, and most
shuffle charge in one way or another.

>> And if you're using it for audio processing, why do you care so much
>> about delay?
>
>There are applications like adaptive noise canceling where processing
delay 
>is crucial.

True, but is the delay through most modern sigma-delta converters
intolerable? Two or three sample delay converters are widely available.

>> -- 
>> Randy Yates
>
>Lamer.

Steve

Hi Steve,

Thank you for your opinion on this.


>>>> Does anyone know a device with a fast SAR ADC (that could be used for

>>>> audio
>>>> processing)? A board with suiting anti-aliasing filters, floating
point
>
>>>> DSP
>>>> and fast DAC would be perfect.
>>>> Have you got an idea, what the minimum expected delay could be?
>>
>>> And if you're using it for audio processing, why do you care so much
>>> about delay?
>>
>>There are applications like adaptive noise canceling where processing
>delay 
>>is crucial.
>
>True, but is the delay through most modern sigma-delta converters
>intolerable? Two or three sample delay converters are widely available.
>
>>> Randy Yates
>>Lamer.
>Steve

Unfortunately every extra sample hurts and reduces the performance of the
algorithm.
Which eval board would you suggest, that has a low overall delay (from
analog in to analog out) with Sigma-Delta converters? Easiest would
probably be a common one that is well supported (I made some bad experience
with boards with really bad documentation).

Thank you in advance!
T.

Remember that when you are comparing SAR versus sigma-delta converters you need to add the delay of external analog anti-alias filters required for the SAR converter to the calculation, unless the signal itself is naturally band-limited to the point where you can convince yourself you don't need any more filtering. 

Bob

>Remember that when you are comparing SAR versus sigma-delta converters you
=
>need to add the delay of external analog anti-alias filters required for
th=
>e SAR converter to the calculation, unless the signal itself is naturally
b=
>and-limited to the point where you can convince yourself you don't need
any=
> more filtering.=20
>
>Bob
>

Good point, Bob. Thanks for that!

Can anyone recommend a well supported development board with really low
delay? 
More than two channels in and out would be good as well...

Thanks!
T.