# SPICE HELP

#### ANALA M REDDY

Joined Aug 14, 2017
22
DELAY= exp[(Vth2-Vth1)/n*Vth]
Is there any way so that i can input this equation to the SPICE tool and plot Delay Vs supply voltage?

#### eetech00

Joined Jun 8, 2013
1,660
DELAY= exp[(Vth2-Vth1)/n*Vth]
Is there any way so that i can input this equation to the SPICE tool and plot Delay Vs supply voltage?
If using LTspice, you could enter the equation into a B device...

#### ANALA M REDDY

Joined Aug 14, 2017
22
If using LTspice, you could enter the equation into a B device...
But is it possible to plot delay vs supply voltage for different values of Vth...I need to do this in order to validate my model against SPICE simulation

#### jayanthd

Joined Jul 4, 2015
902
But is it possible to plot delay vs supply voltage for different values of Vth...I need to do this in order to validate my model against SPICE simulation
Use Proteus. It will plot the required graph.

Provide your circuit and I will simulate it with graph and provide you the results.

#### ANALA M REDDY

Joined Aug 14, 2017
22
My first step would be to implement and simulate an inverter using a particular technology node and plot delay vs supply voltage graph for different values of Vth.

Next i want to validate my model against the simulated one using my proposed equation and compare the 2 graphs...since i m knew to SPICE i dont know how to go ahead with the second step..

I basically want to know how can i enter the mentioned equation n plot the graph for different values of Vth,Vth1, Vth2 and supply voltage?

#### Harsha M V

Joined Aug 15, 2017
1
Use Proteus. It will plot the required graph.

Provide your circuit and I will simulate it with graph and provide you the results.
Is there a way to do in LTspice ?
Because, Proteus isn't free unlike LTspice .

#### jayanthd

Joined Jul 4, 2015
902
Is there a way to do in LTspice ?
Because, Proteus isn't free unlike LTspice .
Most Universities in India and also other parts of the world are using crac...ek version of Proteus and there are many links to it on the net.

I am not encouraging to use cracked softwares.

@anala

To do intense simulation with Proteus you need atleast Core i7 Extreme Processor.

With Advanced Simulation Features in Proteus you can plot voltage, current and power graphs. There are also many type of graphs option for doing the analysis.

It costs only 6k USD. Is it much ? In India people spend 6k USD for buying a Car.

But is it possible to plot delay vs supply voltage for different values of Vth...
[?QUOTE]

In Proteus you can set which parameter (eg: power supply is variable) and then enter the start and end time of plotting graph and it will plot the required graphs. You can plot multiple things in the same graph.

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#### ANALA M REDDY

Joined Aug 14, 2017
22
Most Universities in India and also other parts of the world are using crac...ek version of Proteus and there are many links to it on the net.

I am not encouraging to use cracked softwares.

@anala

To do intense simulation with Proteus you need atleast Core i7 Extreme Processor.

With Advanced Simulation Features in Proteus you can plot voltage, current and power graphs. There are also many type of graphs option for doing the analysis.

It costs only 6k USD. Is it much ? In India people spend 6k USD for buying a Car.
Plotting is secondary for me..my focus is on how i can incorporate the above mentioned equation in the tool and analyze the delay for different values of threshold voltage.

#### jayanthd

Joined Jul 4, 2015
902
Plotting is secondary for me..my focus is on how i can incorporate the above mentioned equation in the tool and analyze the delay for different values of threshold voltage.
Which SPICE tool are you using ?

#### eetech00

Joined Jun 8, 2013
1,660
Is there a way to do in LTspice ?
Because, Proteus isn't free unlike LTspice .
Yes..there is s way to do that.
But I'm not near a computer at the moment..

#### ANALA M REDDY

Joined Aug 14, 2017
22
Which SPICE tool are you using ?
working on both PSPICE and LTSPICE

#### ANALA M REDDY

Joined Aug 14, 2017
22
Yes..there is s way to do that.
But I'm not near a computer at the moment..
can i know how to enter any mathematical expression and obtain the results for the same ?

#### jayanthd

Joined Jul 4, 2015
902
can i know how to enter any mathematical expression and obtain the results for the same ?
In this equation

Code:
DELAY= exp[(Vth2-Vth1)/n*Vth]
What are the min and max values of

Vth, Vth1, Vth2 and n ?

I will see if I can get results in Proteus.

#### Bordodynov

Joined May 20, 2015
2,394
It is example:

For an example of using LTspice, I took the simplest outline. The author of the topic did not give enough information for full-fledged assistance. How does the above equation and supply voltage relate to each other? Without additional information, the question does not make sense. And it turns out like in the Russian proverb:
In the garden of elder (elderberry) , and in Kiev uncle.