Chapter 12 : Field effect transistors

Pg: 541 Ex12.1

In [1]:
from __future__ import division
#initialisation of variables
K= 2 
VGS1= 5 #V
VGS2= 4 #V
VGS3= 3 #V
VGS4= 2 #V
#CALCULATIONS
id1= K*(VGS1-2)**2
id2= K*(VGS2-2)**2
id3= K*(VGS3-2)**2
id4= K*(VGS4-2)**2
#RESULTS
print 'iD = %.f V '%(id1)
print '\n iD = %.f V '%(id2)
print '\n iD = %.f V '%(id3)
print '\n iD = %.f V '%(id4)

iD = 18 V 

 iD = 8 V 

 iD = 2 V 

 iD = 0 V

Pg: 544 Ex12.2

In [2]:
from sympy import symbols,solve
from __future__ import division
#initialisation of variables
KP= 50 #uA/V62
Vto= 2 #V
L= 10 #um
W= 400 #um
Vdd= 20 #mV
R2= 1 #kohms
R1= 3 #ohms
Rd= 11.5 #Mohms
Rs= 1 #kohms
V= 4 #mV
#CALCULATIONS
K= W*KP/(2*L*10**3)
Vg= Vdd*R2/(R1+R2)

x=symbols("x")
vec=solve(x**2-3.630*x+2.148,x)
VGSQ= vec[0]
IDQ= K*(VGSQ-Vto)**2
VDSQ= Vdd+V+L-(Rd+Rs)*IDQ
#RESULTS
print 'VDSQ = %.1f V '%(VDSQ)

VDSQ = 14.3 V

Pg: 548 Ex12.3

In [3]:
from __future__ import division
#initialisation of variables
VGSQ= 3.5 #V
VDSQ= 10 #V
id1= 10.7 #mA
id2= 4.7 #mA
dvgs= 1 #V
id3= 8 #mA
id4= 6.7 #mA
vds1= 14 #V
vds2= 4 #V
#CALCULATIONS
gm= (id1-id2)/dvgs
rd= (vds1-vds2)*10**3/(id3-id4)
#RESULTS
print 'rd = %.1e ohms'%(rd)

rd = 7.7e+03 ohms

Pg: 549 Ex12.5

In [4]:
from __future__ import division
from math import sqrt
#initialisation of variables
RL= 1 #kohms
R1= 2 #Mohms
R2= 2 #Mohms
KP= 50 #uA/V**2
L= 2 #um
W= 160 #um
Vto= 1 #V
IDQ= 10 #mA
VG= 7.5 #V
#CALCULATIONS
K= W*KP/(2*L*10**3)
VGSQ= sqrt(IDQ/K)+Vto
VS= VG-VGSQ
RS= VS*10**3/IDQ
gm= sqrt(2*KP/10**3)*sqrt(W/L)*sqrt(IDQ)
RL1= 1/(1/(RS)+(1/(RL*10**3)))
Av= gm*RL1*10**-3/(1+gm*RL1*10**-3)
Rin= 1/((1/R1)+(1/R2))
Ro= 1/(gm*10**-3+(1/RS))
Ai= Av*Rin/RL
G= Av*Ai*10**3
#RESULTS
print 'G = %.1f '%G

G = 529.7