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  1. #21
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    Re: ft of a transistor - non existent in the documentation.

    and now the S21


    - - - Updated - - -

    Done, I posted before you answer My previous post.



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  2. #22
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    Re: ft of a transistor - non existent in the documentation.

    Try set m of MOS larger, e.g. m=20.

    Anyway your MOS is not modeled well for RF.

    Plot H21.
    ft is a frequency of H21=0dB.
    Last edited by pancho_hideboo; 18th May 2016 at 18:55.



  3. #23
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    Re: ft of a transistor - non existent in the documentation.

    y21? I have ploted the S21 which was what you asked.

    Do you really want the Y21? That would mean to reconfigure the testbench.

    Gonna make the transistor bigger.

    I don't know if you read, but I said that this mosfet is nota RF MOS but I want to know what's the range of frequencies that I can use this transistor. Do you know what I mean?

    There is any other way to check at which extend the model can be used for high frequencies?

    - - - Updated - - -

    What you mean by: "ft is a frequency of y21=0dB." ?



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  4. #24
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    Re: ft of a transistor - non existent in the documentation.

    Sorry. Not Y21.
    H21 is correct.

    Increase m of MOS, e.g. m=20 until S21 >> 0dB.
    Last edited by pancho_hideboo; 18th May 2016 at 19:27.



  5. #25
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    Re: ft of a transistor - non existent in the documentation.

    Okay. Gonna do that. H21? Or S21??



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  6. #26
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    Re: ft of a transistor - non existent in the documentation.

    Quote Originally Posted by AMSA84 View Post
    Okay. Gonna do that. H21? Or S21??
    Plot both.



  7. #27
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    Re: ft of a transistor - non existent in the documentation.

    Did as you suggested, m=20. Same thing.



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    Re: ft of a transistor - non existent in the documentation.

    Quote Originally Posted by AMSA84 View Post
    Did as you suggested, m=20. Same thing.
    gm of your MOS is too small for evaluation of S21 and Gmax.

    So increase m (Instance Multiplier) or Idrain.



  9. #29
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    Re: ft of a transistor - non existent in the documentation.

    I am not forcing Idrain. Should I use a current source? Doesnt make sense. So I just can increase the W Right?

    I think I am gonna leave this and I'll try with a different design kit just for this purpose.



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    Re: ft of a transistor - non existent in the documentation.




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  11. #31
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    Re: ft of a transistor - non existent in the documentation.

    Nice. Gonna try tomorrow. I will come back tomorrow.



  12. #32
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    Re: ft of a transistor - non existent in the documentation.

    "dcblock" and "dcfeed" are very common primitives in RF Simulator.
    http://edadocs.software.keysight.com...ageId=82848179
    http://edadocs.software.keysight.com...ageId=82848195

    However introduction of these is faily recent in Cadence Spectre.

    So you can use "analogLib/dcblock" and "analogLib/dcfeed".

    Quote Originally Posted by pancho_hideboo View Post
    Or use two sp2tswitch.
    One is for gate.
    The other is for drain.
    I used "analogLib/sp2tswitch" in attached example.

    You may use "analogLib/dcblock" and "analogLib/dcfeed"
    instead of "analogLib/sp2tswitch".
    Last edited by pancho_hideboo; 19th May 2016 at 10:44.



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