# How to simulate MAG, MSG, Mason's U of a transistor

1. ## How to simulate MAG, MSG, Mason's U of a transistor

Hi all,

I just have a little question ..... I am trying to characterize a single transistor by plotting it's maximum stable gain (MSG), maximum available gain (MAG), and the Mason's unilateral gain (U).

Has anyone tried to plot these graphs by simulations before ? I have still no idea how to set up the simulation environment in SpectreRF.

Thank you very much ,

DYL

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2. ## Re: How to simulate MAG, MSG, Mason's U of a transistor

Originally Posted by DoYouLinux
I am trying to characterize a single transistor by plotting it's maximum stable gain (MSG), maximum available gain (MAG), and the Mason's unilateral gain (U).
Simply do S-parameter analysis and plot them based on their definition.

Originally Posted by DoYouLinux
I have still no idea how to set up the simulation environment in SpectreRF.
SpectreRF is not needed at all.
S-parameter analysis is a function of Spectre not SpectreRF.

If you believe Direct Plot Form of Cadence ADE blindly, use the followings in Direct Plot Form.
Gmax ; Maximum Available Power Gain
Gmux ; Maximum Unilateral Power Gain
Gmsg ; Maximum Stable Power Gain

See http://www.designers-guide.org/Forum...1205246365/3#3

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3. ## Re: How to simulate MAG, MSG, Mason's U of a transistor

Hi Pancho_Hideboo

I am new to high frequency designs, so there are million of things that I need to clarify, sometimes I post my question in order to double check my understanding again. Anyway, thank you again for your reply.

DYL

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4. ## How to simulate MAG, MSG, Mason's U of a transistor

In cadence spectre plot, the Gmsg and Gmax is the maximum stable gain and maximum available gain. And they could be plotted easily. But the Gumx in spectre is actually the unilateral transducer gain. It is different from U. See the attachment.
If you want to plot Mason's U, you'd better plot it's equation, which is different from Gumx.
I have checked them in spectre.

Good luck,
jimiblues

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