[help] how to switch a current source?

[DreamCat]

I want to generate a triangle wave, and I know that use a const current source to charge a capacitor can get a good linearity of the waveform.

but, when I use very high frequency square wave to switch a CCS cirruit, the current of the CCS has glitch on the rising-edge and falling-edge of the square wave.

it seems that it is caused by the Miller effect. but I have no idea to cancel it.

Anybody know how to resolve this problem?

[TomJackson69]

DreamCat,

This link may help: http://www.edaboard.com/thread180868.html?vm=r

The topic is: how to remove the glitches

Tom

[solutions]

You need a stiffer current source. Have you looked at cascoding it?

The other option is to use it as the tail of a diff amp switch - one side goes to your cap, the other goes to an equivalent impedance.  Draws more power, but glitching is close to zero.

Mother Nature is a cruel whore - she gives nothing you want for free.

[DreamCat]

I'm using a improve current source :
here: http://en.wikipedia.org/wiki/Wilson_current_source#Further_improvement

let me think again...