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  1. #1
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    Using a diode connected transistor model in CST 3D simulation

    I want to have a diode connected NMOS in a 3D CST simulation. I just want a wire loop and in this wire loop, there is a port and this lumped transistor model.

    I simply want to have this in a full 3D simulation.
    Click image for larger version. 

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    It would look like this (maybe), except, instead of a diode, there would be a transistor model.
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    I would like to be able to change the transistor model, but I can just start with a random model such as

    .model AO6407 VDMOS(pchan Rg=3 Rd=14m Rs=10m Vto=-.8 Kp=32 Cgdmax=.5n Cgdmin=.07n Cgs=.9n Cjo=.26n Is=26p Rb=17m ksubthres=.1 mfg=Alpha_&_Omega Vds=-20 Ron=34m Qg=13n)

    How would I go about putting this transistor in diode connected configuration in the simulation?

    transistor_model.zip

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  2. #2
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    Re: Using a diode connected transistor model in CST 3D simulation

    CST Microwave Studio does not simulate active elements..
    Passive components only such as filters,cavities,lumped passive components,antennas etc.



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  3. #3
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    Re: Using a diode connected transistor model in CST 3D simulation

    Quote Originally Posted by BigBoss View Post
    CST Microwave Studio does not simulate active elements..
    Passive components only such as filters,cavities,lumped passive components,antennas etc.
    Just to be clear, Microwave Studio can indeed simulate diodes just fine and it allows you to use a .cir/.net file as a lumped element

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    I realize diodes are technically passive, but i only intend to put in a diode connected transistor, with no additional biasing or anything. It seems like it should be possible.



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    Re: Using a diode connected transistor model in CST 3D simulation

    But the model which you have written above is a nonlinear MOS model.CST cannot understand those statements..
    All you can do is to linearize that diode as you have remarked so diode will have simple small signal AC model..Possible ?? Try..
    But If I were you, I transfer that layout/system/circuit (?) onto Keysight ADS Design Environment if you're able to launch, then I would do my simulations with true nonlinear model..



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    Re: Using a diode connected transistor model in CST 3D simulation

    Quote Originally Posted by BigBoss View Post
    But the model which you have written above is a nonlinear MOS model.CST cannot understand those statements..
    All you can do is to linearize that diode as you have remarked so diode will have simple small signal AC model..Possible ?? Try..
    But If I were you, I transfer that layout/system/circuit (?) onto Keysight ADS Design Environment if you're able to launch, then I would do my simulations with true nonlinear model..
    Nonlinear diode works fine with Transient simulation.
    Click image for larger version. 

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  6. #6
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    Re: Using a diode connected transistor model in CST 3D simulation

    Quote Originally Posted by Nhera View Post
    Just to be clear, Microwave Studio can indeed simulate diodes just fine and it allows you to use a .cir/.net file as a lumped element
    You should check if the excitation level can be changed without repeating the EM analysis of the linear passive model parts. It would be inefficient to repeat the EM calculation if only the diode response changes. That's why we usually split into active part (nonlinear, lumped) and EM part (linear, distributed), for workflow efficiency reasons.
    Last edited by volker@muehlhaus; 22nd June 2019 at 17:34.



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