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Using a DC operating point as parameter

Ron M

Hi,

Just wondered if there is an easy solution to this that does not involve using skill/ocean.

We are running a DC analysis and would like to use a transistor operating point (in our case 'gm') as a parameter to next AC/RF analyses.

In the past we designer just ran a DC in certain condition (PVT/mode) and set the value manually assuming it will be good enough for all other conditions.

Now, we are more sensitive to this parameter and would like to set it up separately for each condition.

Did someone do something like that? Do you an idea how to do it?

Thanks,

Ronen

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  • Andrew Beckett

    Hi Ronen,

    The simplest way to do this would be to have two tests. The first test runs the DC analysis and measures the gm (which you should be able to retrieve using a calculator function such as OP("/M0" "gm") and have as a named output (called, say M0_gm), or even to calculate the resistor value you need to compute. The second test has a variable on the resistor, and then sets that (as a global variable) using calcVal("M0_gm" "firstTestName") - you can drag the output to the global variables and it will fill this in for you. 

    It can also be done with "pre-run scripts" but I think two tests with a relationship between them would be simpler.

    Regards,

    Andrew.

Reply
  • Andrew Beckett

    Hi Ronen,

    The simplest way to do this would be to have two tests. The first test runs the DC analysis and measures the gm (which you should be able to retrieve using a calculator function such as OP("/M0" "gm") and have as a named output (called, say M0_gm), or even to calculate the resistor value you need to compute. The second test has a variable on the resistor, and then sets that (as a global variable) using calcVal("M0_gm" "firstTestName") - you can drag the output to the global variables and it will fill this in for you. 

    It can also be done with "pre-run scripts" but I think two tests with a relationship between them would be simpler.

    Regards,

    Andrew.

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