[sdiy] Problems with linearized SSI2164 ?

Dave dlmanley at sonic.net
Thu Feb 14 20:49:22 CET 2019



On February 14, 2019 5:37:45 AM PST, Mattias Rickardsson <mr at analogue.org> wrote:
>On Thu, 14 Feb 2019 at 00:54, Neil Johnson <neil.johnson71 at gmail.com>
>wrote:
>
>> > In any case, I believe that the circuit Dan was using it in is
>exactly
>> the
>> > one given by Phillip Gallo in the datasheet, and it ain't working. 
>That
>> > tells me that the ICs are defective.
>>
>> In this case, no - the circuit as built by Intellijel was not as
>Irwin or
>> Gallo designed, as the loop compensation capacitor was wrong but a
>factor
>> of 5ish (22p vs. 100p).
>>
>
>I'm glad the error was found and the mystery finally understood! :-)
>HF oscillations seems to be one the most common mistakes we all make,
>and
>then fail to realize for a while, blaming everything else around it
>since
>the behaviour ends up wonky.
>
>I've tested the SSI2164 as drop-in replacement in as many applications
>I
>could and haven't been able to find any differences in behaviour -
>except
>for generally better performance in THD & SNR. So I agree:
>
>But you're right about one thing:  *Good job SSI!*
>>
>
>/mr


This is a GBW/ phase margin issue?  Indicating the SSI part has greater GBW so is less tolerant to a reduced cap value?

-Dave



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