Chapter 6 Small Signal Midfrequency Bjt Amplifiers

Example 6.2 , Page no:175

In [1]:
import math
from __future__ import division

#initialisation of variables
a=0.99 #alpha
Rc=4*10**3 #kΩ
Rl=4*10**3 #kΩ
Re=5*10**3 #kΩ
re=30 #Ω
rb=300 #Ω

#CALCULATIONS
Ai=(a*Rc*Re)/((Rc+Rl)*(Re+re+(1-a)*rb))

#RESULTS
print"The value of Ai=",round(Ai,3);

The value of Ai= 0.492

Example 6.7 , Page no:178

In [2]:
import math
from __future__ import division

#initialisation of variables
hfe=90
Rl=800 #Ω
Rc=800 #Ω
Rb=831 #kΩ
hie=200

#CALCULATIONS
hoe=100*10**-6
Av=-((hfe*Rl*Rc)/(hie*(Rc+Rl+hoe*Rl*Rc))) #voltage gain Av
Ai=((Rb*hie)/(Rl*(Rb+hie)))*Av #current gain Ai

#RESULTS
print"The value of Av=",round(Av,3);
print"The value of Ai=",round(Ai,3);

The value of Av= -173.077
The value of Ai= -34.876

Example 6.8 , Page no:179

In [3]:
import math
from __future__ import division

#initialisation of variables
vl=1.1528 #output voltage
vi=0.250 #input voltage

#CALCULATIONS
Av=-(vl/vi) #voltage gain 

#RESULTS
print"The value of Av=",round(Av,3);

The value of Av= -4.611

Example 6.18 , Page no:185

In [4]:
import math
from __future__ import division

#initialisation of variables
Rs=5 #kΩ
Rf=100 #kΩ
hie=1.1
Rc=10 #kΩ
Rl=10 #kΩ
hfe=50

#CALCULATIONS
d=((1/Rs)+(1/Rf)+(1/hie))*((1/Rf)+((Rc+Rl)/(Rc*Rl)))+((1/Rf)*((hfe/hie)-(1/Rf)))

#RESULTS
print"The value of d=",round(d,3);

The value of d= 0.689

Example 6.19 , Page no:186

In [5]:
import math
from __future__ import division

#initialisation of variables
hfb=-0.99
hib=25

#CALCULATIONS
Rc=2.2*10**3
Rl=1.1*10**3
Re=3.3*10**3
hob=10**-6
Av=((Rc*Rl*hfb)/(hib*(Rc+Rl+hob*(Rc*Rl))))
Ai=-((Re*Rc*hfb)/((Re+hib)+(Rc+Rl+hob*Rl*Rc)))

#RESULTS
print"The value of Av=",round(Av,3);
print"The value of Ai=",round(Ai,3);

The value of Av= -29.019
The value of Ai= 1084.494

Example 6.22 , Page no:189

In [6]:
import math
from __future__ import division

#initialisation of variables
hfe=40
hie=1500

#CALCULATIONS
Rc2=20*10**3 #Ω
Rc1=10**4 #Ω
hoe=30*10**-6
Av2=-((hfe*Rc2)/(hie*(1+hoe*Rc2))) #final-stage voltage gain
Rb2=5*10**3 #Ω
Zin2=(((Rb2*hie)/(Rb2+hie)))/1000 #final-stage input impedance Zin2
Zin21=Zin2*1000
Av1=-((hfe*Zin21*Rc1)/(hie*(Rc1+Zin21+hoe*Zin21*Rc1))) #initial-stage voltage gain

#RESULTS
print"The value of Av2=",round(Av2,3)
print"The value of Zin2=",round(Zin2,3),"Kohm";
print"The value of Av1=",round(Av1,3)

The value of Av2= -333.333
The value of Zin2= 1.154 Kohm
The value of Av1= -26.756

Example 6.24 , Page no:191

In [7]:
import math
from __future__ import division

#initialisation of variables
Av1=0.9879
hfe=100

#CALCULATIONS
R11=90*10**3
R12=100*10**3
R22=90*10**3
R21=10*10**3
Rl=5*10**3
Rc=5*10**3
hie=1*10**3
Rb1=((R11*R12)/(R11+R12))/1000
Rb2=((R22*R21)/(R22+R21))/1000
Av2=-((hfe*Rl*Rc)/(hie*(Rl+Rc)))
Av=Av1*Av2

#RESULTS
print"The value of Rb1=",round(Rb1,3),"Kohm";
print"The value of Rb2=",round(Rb2,3),"Kohm";
print"The value of Av2=",round(Av2,3)
print"The value of Av=",round(Av,3),"Kohm";

The value of Rb1= 47.368 Kohm
The value of Rb2= 9.0 Kohm
The value of Av2= -250.0
The value of Av= -246.975 Kohm

Example 6.26 , Page no:193

In [8]:
import math
from __future__ import division

#initialisation of variables
hfe=100

#CALCULATIONS
Rl=3*10**3 #kΩ
Rc=3*10**3 #kΩ
hie=1*10**3
Av2=-((hfe*Rl*Rc)/(hie*(Rl+Rc)))
Rc1=10*10**3 #kΩ
Re1=1*10**3 #kΩ
Av1=-((hfe*Rc1*hie)/((Rc1+hie)*((hfe+1)*Re1+hie)))
Av=Av1*Av2
Ai1=-((hfe*Rc1)/(Rc1+hie))
Rc2=3*10**3 #kΩ
Ai2=-((hfe*Rc2)/(Rc2+Rl))
Ai=Ai1*Ai2

#RESULTS
print"The value of Av2=",round(Av2,3);
print"The value of Av1=",round(Av1,3);
print"The value of Av=",round(Av,3);
print"The value of Ai1=",round(Ai1,3);
print"The value of Ai2=",round(Ai2,3);
print"The value of Ai=",round(Ai,3);

The value of Av2= -150.0
The value of Av1= -0.891
The value of Av= 133.69
The value of Ai1= -90.909
The value of Ai2= -50.0
The value of Ai= 4545.455

Example 6.27 , Page no:194

In [9]:
import math
from __future__ import division

#initialisation of variables
hfb1=-0.99
hfc2=-100
hic2=500
hib1=50
hic2=500
Av2=0.995

#CALCULATIONS
Rb=33.3*10**3
Re1=5*10**3
Re2=2*10**3
Rl=2*10**3
Av1=-((hfb1*Rb*hic2)/(hib1*(Rb+hic2)))
Av=Av1*Av2
Ai1=-((hfb1*Re1*Rb)/((Re1+hib1)*(Rb+hic2)))
Ai2=-((hfc2*Re2)/(Re2+Rl))
Ai=Ai1*Ai2

#RESULTS
print"The value of Av1=",round(Av1,3);
print"The value of Av1=",round(Av,3);
print"The value of Ai1=",round(Ai1);
print"The value of Ai2=",round(Ai2,3);
print"The value of Ai=",round(Ai,3);

The value of Av1= 9.754
The value of Av1= 9.705
The value of Ai1= 1.0
The value of Ai2= 50.0
The value of Ai= 48.285