#

# $Id: electron.dem,v 1.9 2008/04/30 04:16:05 sfeam Exp $

#

# Electronics demo

#

# Bipolar Transistor (NPN) Mutual Characteristic

Ie(Vbe)=Ies*exp(Vbe/kT_q)

Ic(Vbe)=alpha*Ie(Vbe)+Ico

alpha = 0.99

Ies = 4e-14

Ico = 1e-09

kT_q = 0.025

set dummy Vbe

set grid

set offsets

unset log

unset polar

set samples 160

set title "Mutual Characteristic of a Transistor"

set xlabel "Vbe (base emmitter voltage)"

set xrange [0 : 0.75]

set ylabel "Ic (collector current)"

set yrange [0 : 0.005]

set key box

set key at .2,.0045

set format y "%.4f"

plot Ic(Vbe)

set format "%g"

pause -1 "Hit return to continue"

# Junction Field Effect Transistor (JFET) Mutual Characteristic

# drain current above pinch off

Ida(Vd)=Ido*(1-Vg/Vp)**2

# drain current below pinch off

Idb(Vd)=Ido*(2*Vd*(Vg-Vp)-Vd*Vd)/(Vp*Vp)

# drain current

Id(Vd)= (Vd>Vg-Vp) ? Ida(Vd) : Idb(Vd)

# drain current at zero gate voltage

Ido = 2.5

# pinch off voltage

Vp = -1.25

# gate voltage

Vg = 0

set dummy Vd

unset grid

unset key

#set offsets 0, 1, 0, 0

set title "JFET Mutual Characteristic"

set xlabel "Drain voltage Vd (V)"

set xrange [0 : 4]

set ylabel "Drain current Id (mA)"

set yrange [0 : 5]

set rmargin 12

set label 1 "-0.5 Vp" at 4.1,0.625

set label 2 "-0.25 Vp" at 4.1,1.4

set label 3 "0" at 4.1,2.5

set label 4 "Vg = 0.5 Vp" at 4.1,3.9

plot Vg=0.5*Vp,Id(Vd),Vg=0.25*Vp,Id(Vd),Vg=0,Id(Vd),Vg=-0.25*Vp,Id(Vd)

pause -1 "Hit return to continue"

unset label

unset rmargin

# show off double axes

# amplitude frequency response

A(jw) = ({0,1}*jw/({0,1}*jw+p1)) * (1/(1+{0,1}*jw/p2))

p1 = 10

p2 = 10000

set dummy jw

set grid x y2

set logscale xy

set log x2

unset log y2

set key default

set key bottom center box

set title "Amplitude and Phase Frequency Response"

set xlabel "jw (radians)"

set xrange [1.1 : 90000.0]

set ylabel "magnitude of A(jw)"

set y2label "Phase of A(jw) (degrees)"

set ytics nomirror tc lt 1

set y2tics nomirror tc lt 3

set xtics mirror

set tics out

set autoscale  y

set autoscale y2

plot abs(A(jw)) lt 1, 180/pi*arg(A(jw)) axes x1y2 lt 3

pause -1 "Hit return to continue"

# undo what we've done

reset