how to do AC analysis with switched capacitor CMFB?

[walker5678]

cmfb switched capacitor pnoise spectrerf

HI,
anybody has some good ideas to simulate the AC characteristics of the differential opamp with switched capacitor CMFB circuit? Because the switched capacitor has no DC operating point, so how to deal with it in AC analysis?

thanks.

 

[LvW]

pnoise cmfb switched capacitor

For simulation purposes you have to replace each S/C unit with a time continuous analogon.
There are specific tables how the different switch arrangements are replaced.
The analog replacements can be modelled with delay lines or controlled sources.
The procedure is described, for example, in
Ghausi/Laker: Modern Filter Design - Active RC and Switched Capacitor.

 

[hongmy]

how to read ac analysis

Hi,walker56778
If you have cadence icfb and ADE,you can use SpectreRF. its pss,pnoise adn pac are very useful.

 

[walker5678]

ac analysis

hi, hongmy

can these tools do AC analysis of switch capacitor CMFB circuit without building a linearized model for it ?

 

[hongmy]

yes,spectreRF can.

please read its help docu. spectreRF can simulation many type periodic circuit.

 

[culho]

replace your sc cmfb circuit with some voltage controled voltage sources. connect the differential outputs to 2 vcvs and generate a common-mode voltage.