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gpdk045 vth at dcop is not same as model spec

rfham

Hi, Andrew

I have checked the gpdk045 model report, it's said the vth is obtained using constant current method, the intercept current=Icon*W/L (Icon=1e-8A for 1.1V device and Icon=1e-7A for 1.8V device), Vth unit is V, spec is here

and i simulated use the circuit, VDS=1.1V and sweep the VGS from 0 to 1.1V.

according to the equation constant current method int current = 10u/40n *1e-8A =2.5*e-6 A =2.5uA, check the ids and vth is located at around 320mV, close to the spec, but check at result browser, plot the vth, about 620mV, what is wrong here? thanks a lot.

  • rfham

    please anyone can give some comments? thanks a lot~!

  • Andrew Beckett
    in reply to rfham
    I think this is just a difference in definition. If you look in the bsim4 equations in the documentation it describes how vth is computed.
    I did experiment with setting vthmod=vthcc but that didn’t really make a difference here.
    That said, I didn’t really have time to investigate fully - if you need that for this made-up process, please contact customer support.
    Andrew.

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