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Plotting Output Impedance of an Inverter

nevinalex1234

 Hi

I am using cadence 6.1. I have used DC sweep operation for plotting various parameters, etc variations of VDS with respect to l,w etc..

I have designed a small inverter and i want to measure the output impedance of the same vs Vds . How do i proceed ?

There is no option for plotting ron||rop ?

Parents
  • MicheleA

    Hi,

    I understand you would like to plot the output resistance (rds) of your n and p MOS, versus some DC sweep variable.

    It may be that, while if you perform a single point DC analysis, you are able to print the small signal parameters of your devices, if you try the same after a DC sweep, you are unable to visualize those data. If that's the issue you are facing, I have gone trhough the same: basically, you have to instruct the simulator to save OP device data for each point in the sweep. By default they are discarded (as to spare some room).

    Here is my post, along with Andrew Beckett's (perfect) reply :) 

    /forums/p/21507/1307561.aspx#1307561 

    Once you have rds_n and rds_p, you can just calculate the parallel of those two and insert the expression in the outputs.

    Hope this helps,

    M 

Reply
  • MicheleA

    Hi,

    I understand you would like to plot the output resistance (rds) of your n and p MOS, versus some DC sweep variable.

    It may be that, while if you perform a single point DC analysis, you are able to print the small signal parameters of your devices, if you try the same after a DC sweep, you are unable to visualize those data. If that's the issue you are facing, I have gone trhough the same: basically, you have to instruct the simulator to save OP device data for each point in the sweep. By default they are discarded (as to spare some room).

    Here is my post, along with Andrew Beckett's (perfect) reply :) 

    /forums/p/21507/1307561.aspx#1307561 

    Once you have rds_n and rds_p, you can just calculate the parallel of those two and insert the expression in the outputs.

    Hope this helps,

    M 

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