How to design a large active capacitance (5nF) on chip ?

[mark_nctu]

Need a large capacitance for loop compensation in dc-dc convertor.

How to design a large active capacitance (5nF) on chip ?

Thanks!

 

[JNekas]

Active capacitor ??

Measure capacitor current through the capacitor and amplify it

 

[sunking]

Active capacitor ??

it is diffcult to do.
you can use active cap.

 

[Syukri]

Re: Active capacitor ??

Totally agreed with both senior up there...
In chip cap is very small, as a result of the gap between two layers.

Cox=εo/tox

In order to get large cap. ucan try to use many metal layers but the problems of matching and delay arrise

 

[scottieman]

Re: Active capacitor ??

Measure capacitor current through the capacitor and amplify it

Just a reminder, aware the poles generated from the active capacitor circuit

Scottie

 

[huojinsi]

Re: Active capacitor ??

About active capacitor,u can see the patent of national semiconductor. The patent introduce the mechanism of active capacitor!