Which Ron for Switched-Capacitor Circuit?

[taik]

Hi all,

I think most of the guys here might have read before this paper: Simulating Switched-Capacitor Filters with SpectreRF.

On last line of Pg.11, there is a calculation using 4mkTRon where Ron is the on-resistance of the CMOS switch and is taken to be 2.3k ohms.

My question here is how did the 2.3k come abt?

I did plot the CMOS switch On-Resistance vs Vds curve.

The worst resistance is abt 4.9k ohm. 2.3k ohm is where Vds=0.

So which Ron value is it actually taken from?

Thank you in advance.

 

[taik]

Link to the paper if needed:

https://www.designers-guide.org/Analysis/sc-filters.pdf

 

[lladnar23]

Maybe he's using the VDS=0 condition since the noise is sampled after the switch settles, which implies that VDS has reached 0V. Just a guess, I haven't looked at that paper in a while...