What would be the ideal MOSCAP dimension?

[hrkhari]

Hi Guys

What would be the ideal MOSCAP dimension utilized at power supply rail to ground undesired ac noise for high frequency application?Does this dependant on the frequency of application?.Thank You

Rgds

 

[vistapoint]

Re: MOSCap

I guess you can use all the area left after your layout.

 

[ambreesh]

Re: MOSCap

Dear hrkhari,
We all would like our supplies to be as quiet as possible. But does not happen so.
Your system shall have high PSRR at low frequencies, so it takes care. But after the first dominant pole of the system the PSRR starts to worsen. So look at the frequency where the PSRR is not meeting your minimum expectations, have a cap to take care of frequencies beyond that.
As vistapoint suggested att the area u are not using one can use that. All the dummies of transistor could be configured as cap.
As such we would be using a cap at supply input pin
hope it helps