# set terminal png transparent nocrop enhanced font arial 8 size 420,320 
# set output 'electron.2.png'
set dummy Vd,y
unset key
set offsets 0, 1, 0, 0
set samples 160, 160
set title "JFET Mutual Characteristic" 0.000000,0.000000  font ""
set xlabel "Drain voltage Vd (V)" 0.000000,0.000000  font ""
set xrange [ 0.00000 : 4.00000 ] noreverse nowriteback
set ylabel "Drain current Id (mA)" 0.000000,0.000000  font ""
set yrange [ 0.00000 : 5.00000 ] noreverse nowriteback
Ie(Vbe)=Ies*exp(Vbe/kT_q)
Ic(Vbe)=alpha*Ie(Vbe)+Ico
Ida(Vd)=Ido*(1-Vg/Vp)**2
Idb(Vd)=Ido*(2*Vd*(Vg-Vp)-Vd*Vd)/(Vp*Vp)
Id(Vd)= (Vd>Vg-Vp) ? Ida(Vd) : Idb(Vd)
Ies = 4e-14
kT_q = 0.025
alpha = 0.99
Ico = 1e-09
Ido = 2.5
Vg = 0.3125
Vp = -1.25
plot Vg=0.5*Vp,Id(Vd),Vg=0.25*Vp,Id(Vd),Vg=0,Id(Vd),Vg=-0.25*Vp,Id(Vd)