Cadence - Using a DC simulation to find properties of a transistor

[@emiliomartineziii2980]

It's always a relief when someone who can speak english makes a video 🙏

[@blz1rorudon]

Thank you so much! You saved my final project.

[@sharathbabu8009]

Dear Sir Nice Lecture with practical exposure using cad tools

[@todayiwill1361]

Thanks a lot ! I’m a master thesis student and you help me a lot

[@wallingphd]

That expressionassumes square law operation for the transistor. The simulation here is for a 0.18um device, which is a short channel device, so the current is modified by velocity saturation and other short channel effects.

[@digambarbhole9467]

sir, I have a module that I have created with the help of Mosfet but now I want to plot the resistance of my entire module from the input port but here I am using the sp parameter method to get this plot while using the sp parameter i am applying pulse input as my module resistance changes with the number of pulses applied to it so I want to plot the real-time resistance of my module as it changes with time as it is a function of the number of pulses applied so with sp parameter I am unable to get this plot can you suggest any method where I could plot this

[@sharathbabu8009]

may i dare to request the PDK which you are using in the cad tools? if possible please provide us to do the experiments.....

[@wallingphd]

I cannot share, it is a commercial 65nm RF CMOS process, so it is proprietary.

[@黄琪枫]

Thanks very much! Can I ask a question that has confused me so long? Why the capacitor cgs is negative?

[@wallingphd]

The way that capacitance is calculated is dQ/dV. If this result is negative, it will report a negative value for capacitance, but this is not how it should be interpreted physically.

[@黄琪枫]

Jeffrey Walling But if I need cgs to calculate the bandwidth of the mosfet, should I just take the absolute value of cgs to do it?

[@wallingphd]

@@黄琪枫 To a first order, but this capacitance is very specifically dQgs/dVgs, which is not the total capacitance seen at the gate. But if you are looking to get within 10% of the estimate (for a long channel device), absolute value of cgs from the DC simulation will work.

[@黄琪枫]

Jeffrey Walling That’s great. Thanks.

[@HDgaming345]

Hello Sir. How to find uncox and Vth of a transistor? I'm using TSMC 28nm PDK. Thank you.

[@hamidyadegaramin647]

why the gm value is different than 2*ID/VDSAT?

[@kusha313]

Dear Dr. Walling, Thank you very much for your great video. Do you know how we can extract the input and output capacitance of an inverter with Cadence Spectre?

[@wallingphd]

If you have the transistor dimensions, you can do DC simulations like this. Perhaps an easier way though would be to run a transient simulation where the voltage source has a fixed resistor in series. The input will have an RC like response. You will already know R, and you know that in one time constant you charge to ~67% of the final value, so from the simulated result you can estimate the gate capacitance.

[@sanjayg1728]

Hello, Could tell me how to find the leakage current and the leakage power?

[@aleunsh]

hello Jeffrey! help me pls understand where i can find element transistor N_18_MM P_18_MM cadence device. thanks a lot!

[@deepakroy82]

hey how to find region of mosfet

[@deepakroy82]

do full analysis of regulated current mirror ( output impedence, id vs vds bandth width.

[@Myworld1.9]

sir,can you explain me how to find out parasitic capacitance from a circuit?

[@wallingphd]

From the DC operating point, (Results>Print Results, Select the desired transistor). You will see various capacitances Cgd, Csg, etc...these represent the charge derivative w.r.t. voltage across the various device terminals.

[@deepakroy82]

how to find region of mosfet by tool ???

[@faroteur96]

There's a "region" in the DC operating points when you're editing the DC operating points that you can chose to have displayed.

[@balchandnagar83]

hello sir how to find technology parameter like Vth, U0, E0 etc

[@wallingphd]

From the DC operating point, (Results>Print Results, Select the desired transistor), you can find Vth. u0 and e0 depend on materials and you would have to find them from the process documentation. It will be different for different processes and is not something that can be found from a DC simulation.

[@balchandnagar83]

Thank you very much sir

[@driftingcrystal7285]

@@wallingphd what if I want to sweep the threshold voltage with changing the MOS width, how should I set the output? it seems "OS("/NM0" "vth")" cannot give the value/plot.

[@anassslamti9944]

but this parameters change with L and W and temperature

[@faroteur96]

That's true, however. For most DC simulations you're assuming at room temp so Vth is constant.

[@OmidSalangi-bt2ez]

thank you

[@wii_]

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