Should it be more difficult than this? .subckt 6am4 P G K Bp P K I=(0.01033900924m)*uramp(V(P,K)*ln(1.0+(-0.007076797646)+exp((1.906422463)+(1.906422463)*((116.802414)+(-1169.550306m)*V(G,K))*V(G,K)/sqrt((17.88295266)**2+(V(P,K)-(-11.80479238))**2)))/(1.906422463))**(1.420116524) Cgk G K x.xP Cgp G ...