DSP improvements since the adau1761

Hello,

I'm sure that ADI engineers can give you a more detailed answer, but here's a start... It depends on what you mean by "noise reduction." The -1787 is optimized for the sort of instantaneous noise cancellation in tiny semi-isolated spaces, as done in noise-cancelling headphones. Thus, it has two DSPs -- a super-fast low latency DSP for subtracting external noise at a 700K+ sample rate, and a 50 MIPs DSP for EQ and such. Although the latter DSP is 1761-like, it includes some features not yet in any other SigmaDSP -- foremost of which is a complete math package worthy of a scientific calculator. If you're wondering why in the world it's there, ADI has come up with at least one application thus far -- an Advanced Clipper which uses a hyperbolic tangent function to produce a graduated clip with no jumps in both its output and that output's first derivative. Quite fascinating.

As for other kinds on noise reduction whether beamforming, frequency band DNR, etc. -- I believe you're correct, this chip has nothing on the -1767.

Best regards,

Bob

Hello J.Jeng,

So much of this depends on application. The recent parts we have produced are following/leading the market and that has been in the headphone and hearing aid space. For that space what is super important is the low latency but also power and size. The ADAU1787 design goals from the earlier part, the ADAU1777, were lofty! We were asked to double the instructions for the fast DSP and add a second DSP and add more sample rate converters, both synchronous and asynchronous, add a second serial port and so all this in about the same size and 1/10th the power! My first thought was that it is crazy but we did it!

Notice that a very large DSP with lots of memory and capability is not in the list of requirements/demands. It was power and size. So the part does not have a huge SigmaDSP but it has one and in that small of a space and that low of a power draw it was an accomplishment.

I am not able to discuss parts that are not released on the open forum so there is not much else I can say right now. I see you are using a gmail account and you are in school at the moment so there is no reason to obtain an NDA but stay tuned.

Dave T

Thank you for taking time to respond. This is very interesting information.