Switched capacitors Gm-C Low pass filter

[Manoni_Lo]

Hi,

I have to design a Gm-C switched capacitor filter according to the technique used in this article.




Simulations of cut-off vs duty cycle are good, but i do not understand why the cut-off seems a nonlinear function of duty cycle for small delta.

Thank you for reply

Lorenzo Manoni

 

[FvM]

What do you mean with small delta? What's your duty cycle range?

 

[Manoni_Lo]

My delta is 0.279%. If I try to reduce it by a factor 10 or 100, the cut-off does not scale accordingly.

 

[FvM]

Sounds expectable due to finite switching speed and other parasitic parameters. I presume you get the exact answer by looking into the simulation waveforms.