Orcad PSpice Diode

Hey everyone, I wonder if someone may be able to help me with this problem.

I am trying to compare in theory the effect of increasing a diodes active surface area. I wanted to set up a model in orcad and then iterate it so I get a graph showing perhaps power in vs power out parametrised by surface area. Does anyone know if this is possible? and I cannot seem to find how to alter the active area of diodes when using the capture schematic editor.

Many thanks.

I know how to do this in LTSpice. I suggest you do some reading on the Diode Model in Spice. It has settable area and perimeter parameters. These parameters can be set at the netlist level using a text editor. I suspect that PSpice's graphic user interface is getting in your way...

Editing models in OrCAD PSPICE isn't intuitive, you may need to jab at the F1 key a few times. There's a separate little program that does the editing (OrCAD is a bit of a Frankenstein's monster when it comes to build structure), and the last time I did this - which was a while ago, so my recollection is fuzzy - there was an error window that popped up that required ignoring. I do recall that once I worked out the magic incantation to enable the model editor, I felt the need to write the procedure down and refer to this just about every time thereafter.

thanks for the help guys, I have found the model editor and I am just gonna start by editing the 1N4148 diode model:

.model D1N4148 D(Is=2.682n N=1.836 Rs=.5664 Ikf=44.17m Xti=3 Eg=1.11 Cjo=4p
+ M=.3333 Vj=.5 Fc=.5 Isr=1.565n Nr=2 Bv=100 Ibv=100u Tt=11.54n)

This is the info I can find on the model. How can I find out what each abbreviation refers to?

Thanks again.

Okay, so I have found this:

Is = Saturation current
N = Emission coefficient
Rs = Parsitic resistance
Ikf = Flicker noise coefficient
Xti = IS temperature exponent
Eg = Activation energy
Cjo = Zero-bias junction capacitance
M = Junction grading coefficient
Vj = Junction potential
Fc = Forward bias depletion capacitance coefficient
Isr = ??
Nr = ??
Bv = Reverse breakdown voltage
Ibv = Reverse breakdown current
Tt = Transit time

not sure what Isr and Nr are, something to do with Is and N I'm guessing! So how do I adjust the active surface area?

Cheers