[eispice] Re: behavior test case problems
- From: "Jon Choy" <jonchoy@xxxxxxxxxxx>
- To: eispice@xxxxxxxxxxxxx
- Date: Sat, 23 Dec 2006 16:25:42 -0600
Charles,
You are right about the sign error; but the solution is incorrect. The
answer is around 1.4V. I ran this circuit with an Excel spreadsheet and
writing down the equations as well as writing a Python program that
calculates the DC point using a Newton - Raphson iteration technique it
get's a similar answer of about 1.43V.
Jon
>From: Charles Eidsness <charles@xxxxxxxxxxxxxxxxxxxxx>
>Reply-To: eispice@xxxxxxxxxxxxx
>To: eispice@xxxxxxxxxxxxx
>Subject: [eispice] Re: behavior test case problems
>Date: Tue, 19 Dec 2006 15:46:15 -0500
>
>Hi Jon,
>
>I don't have a lot of experience modelling semi-conductor devices in
>this way so I may be wrong, but shouldn't the current through the PMOS
>device run in the opposite direction w.r.t. the NMOS device? If it's
>turned around, i.e.:
>return -0.5*self.betap*(Vs - Vg - self.vtp)**self.power
>the simulation runs, but gives in an output of 0.7Vs. Which may not be
>what you were expecting?
>
>Cheers!
>Charles
>
>Jon Choy wrote:
> > Charles,
> >
> > Thanks for the feedback. I did notice the typos after I sent the
>case on
> > to you; but they still failed and now I know why. No problem about
>working
> > through the bugs. I anticipated this being sort of an alpha user. Work
>on it
> > when you get a chance, I'm sure you've got your day job as well.
> >
> > Jon
> >
> >
> >
> >> From: Charles Eidsness <charles@xxxxxxxxxxxxxxxxxxxxx>
> >> Reply-To: eispice@xxxxxxxxxxxxx
> >> To: eispice@xxxxxxxxxxxxx
> >> Subject: [eispice] Re: behavior test case problems
> >> Date: Mon, 18 Dec 2006 18:47:03 -0500
> >>
> >> Hi Jon,
> >>
> >> You're not abusing, you're stretching. :) It was intended to be used in
> >> that way, but you're the first to try it.
> >>
> >> It looks like I have some work to do on error messages. They're way to
> >> cryptic, especially for the new PyB device. I'll see what I can do.
> >>
> >> Your B-Element based model uncovered a bug in the calculon library's
> >> parser. It requires a space between the '-' sign and constants. I've
> >> fixed it in my stream and it will be fixed for the next release but for
> >> now you can just add a space. Also, the B element doesn't recognize the
> >> 'GND' identifier, it only recognizes 0 as a ground indicator. I can add
> >> GND as well but I'm hoping that as soon as we get this PyB element
> >> working the only use for the old B element will be for porting in
>Spice3
> >> decks which only use 0.
> >>
> >> If you change:
> >> d.pmosx = dev.B('4', GND, 'i',"0.5*2e-6*(v(1,4)-0.7)^2")
> >> to:
> >> d.pmosx = dev.B('4', GND, 'i',"0.5*2e-6*(v(1,4) - 0.7)^2")
> >>
> >> and:
> >> d.nmosx = dev.B(4, GND, 'i',"0.5*5e-6*(v(4,GND)-0.7)^2")
> >> to:
> >> d.nmosx = dev.B(4, GND, 'i',"0.5*5e-6*(v(4,0) - 0.7)^2")
> >>
> >> The simulation runs, until it fails to linearize. I'll have to fiddle
> >> with the simulator to get it working further than that, which will take
> >> a little bit longer. I'll post again once I get it working.
> >>
> >> The two PyB based models had a couple of typos. The lines:
> >> def model(self, Vg, Vs)
> >> should have a 4th argument (because you defined 3 input arguments), you
> >> can change them to something like:
> >> def model(self, Vg, Vs, Vp)
> >> Also, for the second model the if statement references vtp but it
>should
> >> reference vtn, i.e.:
> >> if ((Vg - Vs)> self.vtp):
> >> should be:
> >> if ((Vg - Vs)> self.vtn):
> >>
> >> Once you make those two changes it should run as far as the 'failed to
> >> linearize' as well.
> >>
> >> I'm sure with some useful messages those two typos would have popped
> >> right out. It's tough to debug when every error message is "TypeError:
> >> bad argument type for built-in operation". I'm guessing it's really
> >> referring to some bug in the way I'm passing error messages between C
> >> and Python, I'll look into it.
> >>
> >> Thanks for having patience as we work through the bugs, and I'll get
> >> back to you on those 'failed to linerise's'
> >>
> >> Cheers,
> >> Charles
> >>
> >>
> >> Jon Choy wrote:
> >>
> >>> I've tried a couple of behavior cases that don't seem to run. I hope
>I
> >>> haven't abused the capability. I'm simply seeing if a mos divider
> >>>
> >> circuit
> >>
> >>> will work. I have two devices and behavioral nmos and pmos with the
> >>>
> >> gate,
> >>
> >>> drain of both the pmos and nmos tied together. I have tried three
> >>>
> >> different
> >>
> >>> cases. Let me know what you think.
> >>>
> >>> #!/usr/bin/python
> >>>
> >>> from eispice import *
> >>>
> >>> # -- PyB Defined Model --
> >>> class pmos_sat(dev.PyB):
> >>>
> >>> def __init__(self, p, n, g, s, b, kp=2e-6,wp=2,lp=1,power=2.0):
> >>> dev.PyB.__init__(self, p, n, Current, v(g), v(s), v(b))
> >>> self.kp = kp
> >>> self.wp = wp
> >>> self.lp = lp
> >>> self.vtp= 0.7
> >>> self.betap = kp*wp/lp
> >>> self.power=power
> >>> def model(self, Vg, Vs):
> >>> if ((Vs - Vg)> self.vtp):
> >>> return 0.5*self.betap*(Vs - Vg - self.vtp)**self.power
> >>> else :
> >>> return 0
> >>> class nmos_sat(dev.PyB):
> >>>
> >>> def __init__(self, p, n, g, s, b, kn=5e-6,wn=2,ln=1,power=2.0):
> >>> dev.PyB.__init__(self, p, n, Current, v(g), v(s), v(b))
> >>> self.kn = kn
> >>> self.wn = wn
> >>> self.ln = ln
> >>> self.vtn= 0.7
> >>> self.betan = kn*wn/ln
> >>> self.power=power
> >>> def model(self, Vg, Vs):
> >>> if ((Vg - Vs)> self.vtp):
> >>> return 0.5*self.betan*(Vg - Vs - self.vtn)**self.power
> >>> else :
> >>> return 0
> >>>
> >>> # Now to use the model
> >>> kp = 2e-6
> >>> wp = 2
> >>> lp = 1
> >>> vtp= 0.7
> >>> betap = kp*wp/lp
> >>> power=2
> >>> kn = 5e-6
> >>> wn = 2
> >>> ln = 1
> >>> vtn= 0.7
> >>> betan = kn*wn/ln
> >>>
> >>> d = Deck('PyB Defined Behavioral MOS divider')
> >>>
> >>> d.V0 = dev.V(1, GND, 3.3)
> >>> #d.pmosx = pmos_sat(4, GND, 4, 1, 1)
> >>> #d.pmosx = dev.B('4', GND, 'i',"0.5*betap*(v(1,4)-vtp)^2")
> >>> d.pmosx = dev.B('4', GND, 'i',"0.5*2e-6*(v(1,4)-0.7)^2")
> >>> #d.nmosx = nmos_sat(4, GND, 4, GND, GND)
> >>> #d.nmosx = dev.B(4, GND, 'i',"0.5*betan*(v(4,GND)-vtn)^2")
> >>> d.nmosx = dev.B(4, GND, 'i',"0.5*5e-6*(v(4,GND)-0.7)^2")
> >>> d.rout = dev.R(4,GND, 100000)
> >>>
> >>> d.op()
> >>>
> >>> d.plot()
> >>>
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