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switched capacitor in cadence (Read 4248 times)
Mahyar
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switched capacitor in cadence
May 22nd, 2009, 3:34pm
 
Hi
I am trying to design a switched capacitor sampling system in virtuoso schematic editor. But I don't know how to:
1- Generate non-overlapping clocks.
2- How to model the switches? should I use like nfet or there are special switches?

Thank you,
M
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HdrChopper
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Re: switched capacitor in cadence
Reply #1 - May 22nd, 2009, 5:26pm
 
A simple approach using ideal components:

1) For non-overlapping clocks just define a variable for the clock period - say Tck. The use two vpulse sources where the first one has a period Tck and a duty cycle of 49.5%. The second source will have the same period and duty cycle but a delay equal to 0.5Tck.
In this way you can change Tck and keep the non-overlapping feature of your clocks.
2) there is an ideal switch in the analogLib simply called "switch". It is voltage controlled and therefore you need to set the Vth high and low and also you can set the resistanc in ON state for such switch.

With these two ideal components you could start designing your SC system.

Regards
Tosei
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Keep it simple
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