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Transistor level design in " Cadence "

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thisissush

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transistor level design

Hi,

I am trying to Optimize an Amplifier Circuit using Cadence.
I need some way to calculate threshold voltage of a transistor and use it in the Optimizer tool.
eg. I have to define an Output X , where X = Vgs(M1) - Vth(M1)


Can someone please tell me how to get the Vth(threshold voltage) for a transistor in Cadence ?


Thank You for your help.
 

cadence optimization dc

You can find the threshold voltage under the DC operating point information. But, I think that information will be useless for optimization, because the threshold voltage depends on the channel length for short channel processes (Vth is not a constant).
Actually I wouldn’t spent time on optimization, if your optimization is based on the square law model and you are using a modern CMOS process. It will be off.
 

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    thisissush

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optimization ocean cadence

No, one reason why I am using optimization is that I want the transistor to be on. And yes Vth varies , that is why I need the Vth for particular design,
Eg. For the 2nd iteration of Optimization if W = x & L = y for a transistor I want an expression that gives me Vth at this iteration .

Is there any way by which this can be done ??
 

transistor-level cadence

Forget about this. Vth is a weird function of L, W etc. If you want to involve Vgs-Vth why don't you just check if Cadence has a variable for this. Something like Vth_disatance or Vov.
 

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    thisissush

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number of transistor cadence

Yeah , that is what I am asking for . Does it have a variable like that ?
I tried but couldn't find one.
 

how to find the threshold voltage of a transistor

You can try to implement you optimization algorithm into Ocean, here you can automate the howl thing and you have the chance to grab the v_th from the operating point analysis.
 

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    thisissush

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transistor area*cadence

Actually , I am supposed to compare Cadence Optimization tool with an other tool. So I have to do it in Cadence itself.
 

transistor level optimization tool

Have you tried with waveform calculator (wavescan)?
In wavescan, just select "info" in "Analysis selection choices" field.
With this you can plot the 'Vth' (for detail go through cadence manual/help).


Hope this will help.
 

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    thisissush

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cadence optimization

vds-vth is for sure one of the DC oppoint parameters, the name can depend on your models

Why do not you consult with the DC operating point parameters section in your models/technology documentation?
 

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    thisissush

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