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bypassing antialiasing filter of TLV320AIC23

Started by murselonder June 15, 2007
Hello,

I have been using C6713 DSK. My question is; Is there antialiasing
filter in front of  AIC23 codec of DSK. If yes, can bypass (omit,
cancel) it?

In other words, can I sample over 48 kHz frequencies with aliasing
intentionally.


murselonder wrote:

> Hello, > > I have been using C6713 DSK. My question is; Is there antialiasing > filter in front of AIC23 codec of DSK. If yes, can bypass (omit, > cancel) it?
AIC23 is delta-sigma codec. Thus the aliasing occurs at the frequency range of several MHz. It is very unlikely to see it unless you deliberately apply a signal generator directly to the input of the codec.
> In other words, can I sample over 48 kHz frequencies with aliasing > intentionally.
If you just want do see how the aliasing sounds like, you can decimate the digital signal without filtering. Vladimir Vassilevsky DSP and Mixed Signal Design Consultant http://www.abvolt.com
murselonder <murselonder@yahoo.com> wrote in news:1181921715.561258.174770
@m36g2000hse.googlegroups.com:

> Hello, > > I have been using C6713 DSK. My question is; Is there antialiasing > filter in front of AIC23 codec of DSK. If yes, can bypass (omit, > cancel) it? > > In other words, can I sample over 48 kHz frequencies with aliasing > intentionally. >
I don't think yo0u got the answer to your question. You cannot defeat the antialiasing filter in this part. As mentioned, this part is a sigma delta part. It actually samples at 64 to 256 times the apparent sample rate. You may want to search on delta sigma or sigma delta to get a better understanding of how this works. The part can be stretched a bit by overclocking assuming that you have 3.3V supplies. You might be able to sample as high as 150k. You need to change the MCLK to accomplish this. It is not the part to use for undersampling IFs etc. If you need something that works a bit higher, the AK4620 from AKM is good to 200k sampling with better performance than the AIC23. -- Al Clark Danville Signal Processing, Inc. -------------------------------------------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com
Hi all,

Thanks for your kindly replies.

To proof subsampling, I have generated suitable signals much more
greater than 48 kHz tried to sample it by AIC23 codec of C6713 DSK. It
was unsuccessful
 I have designed same system in Matlab/Simulink. Be sure that it
works.

I am sure that there has to be antialiasing filter. If it can be
bypassed I am lucky. I have read its technical docs. But I could not
reach my answers.

http://focus.ti.com/lit/ds/symlink/tlv320aic23b.pdf

Best Regards

murselonder <murselonder@yahoo.com> wrote in news:1182168483.152973.103110
@g4g2000hsf.googlegroups.com:

> Hi all, > > Thanks for your kindly replies. > > To proof subsampling, I have generated suitable signals much more > greater than 48 kHz tried to sample it by AIC23 codec of C6713 DSK. It > was unsuccessful > I have designed same system in Matlab/Simulink. Be sure that it > works. > > I am sure that there has to be antialiasing filter. If it can be > bypassed I am lucky. I have read its technical docs. But I could not > reach my answers. > > http://focus.ti.com/lit/ds/symlink/tlv320aic23b.pdf > > Best Regards > >
You can't bypass the antialiasing filter. The corner is a function of the sampling rate in this part. -- Al Clark Danville Signal Processing, Inc. -------------------------------------------------------------------- Purveyors of Fine DSP Hardware and other Cool Stuff Available at http://www.danvillesignal.com