[SOLVED] Voltage-dependant Resistance in PSPICE

[msmol]

Hello everyone, I´m trying to generate a Single Electron Transistor in PSPICE, so I need to create a resistor whose resistance value varies with voltage.

The equation that defines the resistance value is:

R=(0.02/(0.2e-9-2*0.02/(2*300e6+220e6*cos(40*3.14*V(node 1,node 2)))))/1)

I was trying with variable resistances but they don´t work for what I need. Once I have got this, I will run a DC sweep analysis.

Thakns in advance.

 

[dick_freebird]

If you can fit that function "well enough" with a polynomial
series, then a "B source" (poly vcvs) might do it for you.
If you absolutely must implement the function as written,
then look to veriloga implementation (if PSpice supports that).

 

[BradtheRad]

An optocoupler might fit the purpose. Or as an alternate, place a photo-resistor near a light bulb (or led, or combination of both). Can you find suitable components provided in the simulator?

 

[FvM]

Read about "analog behavior modeling" in your PSpice manual.

 

[LvW]

Hello everyone, I´m trying to generate a Single Electron Transistor in PSPICE, so I need to create a resistor whose resistance value varies with voltage.

A voltage-dependent resistor - do you think this is a simplified transistor model?
How does a transistor react upon a change of the collector voltage - and how does a resistor react?
I rather think you need a voltage-controlled current source as a simple model.

 

[msmol]

A voltage-dependent resistor - do you think this is a simplified transistor model?

It´s a phenomenological model for this kind of transistor. I need this transistor to build a bigger circuit to reproduce some characteristics of biological polymers. So, my only remaining problem till today is how to build this voltage-variable resistance, as it is suggested in the bibliography.

I suppose it´s kind obvious that I came to the electronic´s world from a different field.

 

[LvW]

.........voltage-variable resistance, as it is suggested in the bibliography.

Please, can you show us the source of this kind of (false) information?

 

[msmol]

Please, can you show us the source of this kind of (false) information?

Check here: http://sci-hub.cc/10.1007/s10470-015-0491-5

Thanks!

 

[FvM]

So, my only remaining problem till today is how to build this voltage-variable resistance

Problem is that each SPICE variant has a different behavioral modeling syntax. Need to understand how it works in PSpice.

 

[andre_luis]

I was trying with variable resistances but they don´t work for what I need.

There are lot of examples on the Web about voltage-controled-resistor SUBCKT models, therefore it is not clear what did not work for you. With any change you could insert your function there.

 

[FvM]

therefore it is not clear what did not work for you

Apparently the OP uses SPICE code from the paper linked in post #8. It has a resistor with a behavioral expression for the resistance, this modeling method doesn't work in PSpice. Need to refer to controlled sources.

 

[LvW]

Hello everyone, I´m trying to generate a Single Electron Transistor in PSPICE,

msmol - sorry, at first look I didn`t recognize that you are speaking about a "single-electron device". Instead, I have assumed that you were trying to find a simple model for the classical BJT.
Since I have no experience with SET`s, please forget my former contributions.

 

[msmol]

therefore it is not clear what did not work for you. With any change you could insert your function there.

I need a resistor whose resistance value must follow the above equation. At first, I thought that with a PSPICE R_var part I could solve this, but it did not work. I was not sure what way I had to follow, so with the comments here and surfing the web I choosed the voltage-controlled current-source option.

Thanks!

- - - Updated - - -

msmol - sorry, at first look I didn`t recognize that you are speaking about a "single-electron device". Instead, I have assumed that you were trying to find a simple model for the classical BJT.
Since I have no experience with SET`s, please forget my former contributions.

Roger that. Anyway, I think I have already found a solving method. Now it is time to make it work the best way possible in the simulator.

Thanks again for everyone.

 

[msmol]

Hi people, when I thaught I had solved this, I realized I keep stuck in this. I have built a variable resistance resistor, combining a voltage-controlled voltage source (VCVS) with a voltage-controlled current source (VCCS).

The equation that leads the resistance value is:
R=(CVp/(CI2-2*CVp/(2*CR1+CR2*cos(CF1*pi*V(node 1,node 2)))))/K) , where CVp,CI2,CVp,CR1,CR2 and CF1 are constants.

So, the VCVS feeds the VCCS with the equation:

((CVp/(CI2-(2*CVp/(CR1+(CR2*COS(CF1*pi*V(G)))))))/K)



and the VCCS creates a current trough this operation:

V(G)/(V(EaG, GND)+1u) ,

where V(G) is the voltage that controls the resistor, EaG is the node that connects the VCVS with the VCCS. GND is the ground.

The input and output of this two-elements subcircuit connects this "variable resistor" with the rest of the circuit.

The problem is that the results I obtain from my circuit don´t match with the published results, from which I copied this design.

I strongly think the problem is due to this variable resistance. So, Does anyone see any mistake, or can suggest some improve?

Thanks all, have a nice day.