# Ngspice to PSpice conversion

Discussion in 'General Electronics Chat' started by captainkirk, Jun 1, 2012.

1. ### captainkirk Thread Starter New Member

Jun 1, 2012
1
0
Hi All,

I have a piece of Ngspice code that I need to convert to PSpice. I feel it is a simple matter of syntax but I have so far failed to make it work.

The code models a Memristor with thresholding ability (the fourth fundamental component along with resistors, capacitors, and inductors)

The code is as follows:

.subckt memristor plus minus PARAMS: Ron=1K Roff=10K Rinit=5K alpha=0 beta=1E13 Vt=4.6
Bx 0 x I='(f1(V(plus)-V(minus))>0) && (V(x)<Roff) ? {f1(V(plus)-V(minus))}: (f1(V(plus)-V(minus))<0) && (V(x)>Ron) ? {f1(V(plus)-V(minus))}: {0}'
Cx x 0 1 IC={Rinit}
Rmem plus minus r={V(x)}
.func f1(y)={beta*y+0.5*(alpha-beta)*(abs(y+Vt)-abs(y-Vt))}
.ends

The code explanation is as follows:
- The memristive system is realized as a sub-circuit combining a behavioral resistor R, a current source ↑, and a capacitor C.
- The second line of code (Bx ...) defines the current source with the current specified through ternary functions. (A ternary function is defined in the code as a ? b : c , which means IF a, THEN b, ELSE c [17].) The purpose of these functions is to limit RM between Ron and Roff.
- The third line of the code specifies the capacitor C (Cx ...) with an initial condition.
- The fourth line (Rmem ...) defines the behavioral resistor whose resistance takes the same numerical value as the voltage across the capacitor.
- The next line (.func ...) provides the function f according to Equation (not important here)

If you can help me in any way that would be great!!

Many thanks
Captainkirk