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PMOS current source I-V characteristics (Read 2868 times)
Harian
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PMOS current source I-V characteristics
May 02nd, 2017, 1:39pm
 
Hi Everybody,
i have a basic Pmos I-v Characteristics question. A PMos in cadence is connected as following(pls, see the below picture)
While simulating it, i got pmos diode like curve not a normal pmos I-V curve as following https://en.wikipedia.org/wiki/MOSFET#/media/File:IvsV_mosfet.svg
can some one explaint he difference. I am simulation with cadence virtuoso. I would appreciate any help.. thanks
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Pmos.png
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Harian
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Re: PMOS current source I-V characteristics
Reply #1 - May 2nd, 2017, 1:41pm
 
Getting this curve whilw simulation,, But i think it is the typical i-v curve of pmos diode conencted,,isnot it?
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I-V.png
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ULPAnalog
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Re: PMOS current source I-V characteristics
Reply #2 - May 2nd, 2017, 1:48pm
 
What is the gate source voltage?
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Harian
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Re: PMOS current source I-V characteristics
Reply #3 - May 2nd, 2017, 1:53pm
 
i have set to 0.9 volts i.e. Vgs=-2.3 v,, i have slo done parametric simulation sweeping the Vds from -3.3 to 0 and Vgs from -3.3 to 0 also.. the result is always the same curve.. then i have simulated A nmos with the polarity reversed,, it was the same result.. I am thinking ,, it might be simulation equation used,,thx for reply
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Nyquist
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Re: PMOS current source I-V characteristics
Reply #4 - Oct 15th, 2018, 11:23am
 
Hi Harian,

    you have connected gate to a constant voltage and swept the Source voltage. In effect, you are actually sweeping VSG and plotting the Source current. The plot looks correct.

If you need to plot the ID-VDS Characteristics, then you need to connect a voltage source between Source and Gate (VSG). Now you can sweep VSD for different values of VSG to get the plot you want.

Nyquist
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