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custom VCCS

Sali

Dear all

I want to design a vccs to implement this function:

I(y)<+ tanh(V(x));

I have done that using a verilogA model and I connect it in the cadence circuit which is as in the attached file, the model itself works fine but I want it to act as a real electronic component when connected to the circuit, by means when I change the output resistance the output current from this component should be changed accordingly as in the real electrical circuits, how can I do that, the current is always fixed and not affected by the resistor next to it. Because at the end I'll do a lab work by which I will use a similar component .

I read about bsource but I did not find it in any of the libraries !

any suggestion will be appreciated.

Thank you

  • Andrew Beckett

    Whether you use VerilogA or bsource is not the point here - it's a matter of how you formulate the equation.

    Maybe you want something like:

    I(x,y) <+ tanh(V(x,y));

    The idea is that you want there to be a relationship where the current through the branch is a function of the voltage across it. I don't really know what you're trying to achieve though!

    Currently you are measuring the voltage at the input 9to ground), and generating an ideal current at the output (to ground); there is no current flow through the device itself.

    By the way, the bsource component is available in analogLib from IC617 ISR6 onwards.

    Regards,

    Andrew.

  • Sali
    Thanks Andrew for your reply.
    Actually I have a device in the lab made of an organic material and it generates tanh shape, I want to choose values for both R and C in the simulator and compare the output with the lab results.
  • Sali
    I tried writing V(x,y) but when I change the output resistor , it does not affect the output current which is does not happen in the real situation.
    Any other suggestion will be appreciated.
  • Andrew Beckett

    Given that in VerilogA it's quite straightforward to write equations for a conservative system, it must just be that you've not captured the equation correctly. You can write an equation that relates the current through a branch to the voltage across it or vice versa - so it's easy to describe a capacitor, an inductor, or a resistor or some complex relationship which has elements of all of them in some non-linear way.

    Unless we are able to know how the actual measured data was made, and how it behaves, I doubt anyone can give you a suggestion as to what you should be doing - we're in the dark here!

    Regards,

    Andrew.

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