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# How can I find the effective resistance of switched capacitor resistor in cadence virtuoso?

#### Asra12

##### Newbie
How can I find the effective resistance of switch capacitor resistor in cadence virtuoso?

I try to use the s-parameter analysis but I don't get the correct resistance. Measured and calculated ones are different.

#### FvM

##### Super Moderator
Staff member
Cadence Virtuoso is no analog simulator, I guess you are referring to Cadence Spectre. SC circuits have to be analyzed with periodic AC (pac), periodic S-parameter (psp) or periodic steady state (pss). Do you?

#### Asra12

##### Newbie
Cadence Virtuoso is no analog simulator, I guess you are referring to Cadence Spectre. SC circuits have to be analyzed with periodic AC (pac), periodic S-parameter (psp) or periodic steady state (pss). Do you?
Thank you for the reply. Yes, I am referring to the cadence spectre. Can you guide me on how to do periodic S-parameter analysis?

#### FvM

##### Super Moderator
Staff member
I'm not familiar with Spectre. Believe there's plenty of information in the reference and user manual.

#### dick_freebird

S-parameters are small signal and a switched capacitor circuit is
absolutely not that.

Do not expect the tool to "tell you stuff" without asking it the
right questions in the right way (according to it).

I recommend you first find the theory for the SC attributes you
are after and then worry about setting up a proper simulation of
it. What's the setup, what's the equation, then how to set conditions
and pick results.

#### D.A.(Tony)Stewart

I do not use any Cadence Tools, but I generated this result using AI.

In Cadence Spectre, you can find the equivalent series resistance (ESR) of a capacitor by performing an AC analysis of the circuit that includes the capacitor. Here are the steps to follow:
1. Open the circuit schematic in Cadence Spectre.
2. Create an AC analysis simulation by going to the menu bar and selecting "Simulate" > "Analysis Type" > "AC Analysis".
3. Set the frequency range of the analysis by going to the menu bar and selecting "Simulate" > "Analysis Setup". In the Analysis Setup window, set the Start Frequency, Stop Frequency, and Number of Points according to the range of frequencies you want to analyze.
4. Add the capacitor whose ESR you want to measure to the circuit schematic.
5. In the AC Analysis window, select the capacitor by clicking on it and then right-click to open the Properties dialog.
6. In the Properties dialog, under the "Model" tab, select the appropriate capacitor model that includes ESR.
7. Run the AC analysis simulation by going to the menu bar and selecting "Simulate" > "Run". The simulation will generate a frequency response plot that includes the ESR of the capacitor.
8. Analyze the frequency response plot to determine the ESR of the capacitor. The ESR is the slope of the impedance vs. frequency curve at the frequency of interest.