[sdiy] 2164 stability values

[houshu at muj.biglobe.ne.jp]

Hello Neil,

Thank you very much for the detailed info.

I understand that my rough simulation was so lucky.
Change of stability by the input resistors of 10k or bellow was also observed.

Sam HOSHUYAMA

> 2018/06/30, 19:36, Neil Johnson <neil.johnson71 at gmail.com> wrote:
> 
> Hi Sam,
> 
> > You should not change the phase compensation network.
> > 
> > I made a rough simulation of the internal circuit of 2164. It is not reliable
> > for design but useful to qualitative understanding. It showed that the input
> > resistor (30k) has almost no influence on the stability.
> > I tested 10k to 100k and the difference is just the gain which is reverse
> > proportional to the resistor value.
> > 
> > Stability (peak frequency and the height in the frequency response)
> > varies with gain CV. I guess the compensation network covers all the
> > ranges as far as the input resistor value is over 10k.
> 
> Be aware that rough simulations rarely include all the parasitics and
> actual silicon behaviour that results in actual performance, and in
> particular the effects of phase shifts and parasitic capacitances that
> cause poles in the response.
> 
> In this case, a couple of us on this list have been working with Sound
> Semiconductor Inc (SSI) who have released their own version of the
> 2164 in the guide of the SSI2164. As they have the original SSM2164
> designer on their team the investigation into the tuning of the
> compensation network has been most interesting and fruitful. For
> example, here is the latest version of the SSI2164 datasheet:
> http://www.soundsemiconductor.com/downloads/ssi2164datasheet.pdf
> 
> Note the comment that for input resistors of 10k or below they say
> that you need to change the input compensation network. I have more
> detailed information to hand which I believe will be going into the
> next version of the datasheet.
> 
> Neil
> --
> http://www.njohnson.co.uk