Opamps bypassing inquiry

jean-paul

Ex-Moderator
2002-09-20 7:20 am
Germany
They often do screw up the sound when used as bypass caps. I have tried this a lot and don't use ceramic caps anymore for bypassing. My experience is with standard ceramic and Kemet X7R multilayer caps. One good electrolytic cap per rail and one 100 nF film cap from + to - on the opamps supply pins is what I use mostly. Key is to use all three caps as close to the pins as possible for optimal results.

In clock circuits and other RF related schematics ceramic caps are needed because of their RF characteristics.
 
This is a bit off topic but the CS8412 has an analog grnd pin. Should this be connected to the digital grd or the analog grnd? Doesn't this receiver chip work with digital signal only? Why there is an analog grnd pin?

I have run separate ground plane for digital and analog section in my DAC. I connected the two near the main power supply capacitors. It this good or bad?
 
quantran said:
This is a bit off topic but the CS8412 has an analog grnd pin. Should this be connected to the digital grd or the analog grnd? Doesn't this receiver chip work with digital signal only? Why there is an analog grnd pin?

I have run separate ground plane for digital and analog section in my DAC. I connected the two near the main power supply capacitors. It this good or bad?

Hi

http://www.tentlabs.com/Info/Articles/Supply_decoupling.pdf

remember, currents run in circles......

cheers
 
Ok so how do you do the bypass to ground on opamps which dont have a ground on them just +V and -V. Do you literaly just run a cable all the way around the board to the ground plane. Pr can i use one of the NC pins on the chip and use this to get to the back side of the board and them run a wire from this solder point to gorund?

I guess the really question i am asking is is it ok to connect something to the no connect pins of a chip so i can take the ground through the leg to the other side of the board where the ground plane is?

Any help gratefully received.

Also for by-passing my ad825 what would seem like a good set up i have got to hand 1uf, 0.1uf and0.01uf Wima's. Would these be any good and in what cobimeation. also have some backgate 100uf but i guess these are too big for by-pass application


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