Decoupling or Bypass Capacitors

Thread Starter


Joined May 10, 2011

I have following doubts about Decoupling or Bypass Capacitors, please clarify

(1) Different b/w Decoupling or Bypass Capacitor in one line.

(2) For a MPU or any IC having 'N' Vcc (say 3V) pins how many caps i have to use ??

Thanks in advance.

Thread Starter


Joined May 10, 2011
Ya Bertus,

I have studied that, but for (2) question i didn't get the answer.
In some circuits they use 1 cap for 2 Vcc pins but in some circuit they use 1cap per 1 Vcc pin, why is that?

Ans for(1) :According to me both are capacitors with different name depending on
-their frequency characteristics (diff. value)
-place where it is used.
am I right???


Joined Mar 24, 2008
A lot of it depends on how noisy the circuits are, and how noise critcial they are. Many cases it works out it is cheaper to have a few extra 1¢ parts than to have it occasionally become intermittent due to noise issues.


Joined May 8, 2011
My personal preference is to slap a 0.1uF cap across the supply and ground for each IC I use, for the very small cost and space of the caps, it's well worth it in eliminating little glitches that digital chips in particular don't like.