Chapter 14 , Bipolar Junction Transistor

Example 14.1 , Page Number 308

In [1]:
import math

#Variables

IE = 10                     #Emitter current (in milli-Ampere)
IC = 9.8                    #Collector current (in milli-Ampere)  

#Calculation

IB = IE - IC                #Base current (in milli-Ampere)

#Result

print "Base current is ",IB," mA."  

Base current is  0.2  mA.

Example 14.2 , Page Number 310

In [2]:
import math

#Variables

IE = 6.28                     #Emitter current (in milli-Ampere)
IC = 6.20                     #Collector current (in milli-Ampere)  

#Calculation

alpha = IC / IE               #Common base current gain   

#Result

print "Common-Base current gain is ",round(alpha,3),"."  

Common-Base current gain is  0.987 .

Example 14.3 , Page Number 310

In [3]:
import math

#Variables

alpha = 0.967                  #common base current gain
IE = 10                        #Emitter current (in milli-Ampere)

#Calculation

IC = alpha * IE                #Collector current (in milli-Ampere)
IB = IE - IC                   #Base current (in milli-Ampere)

#Result

print "Base current is ",IB," mA." 

Base current is  0.33  mA.

Example 14.4 , Page Number 311

In [4]:
import math

#Variables

IE = 10                        #Emitter current (in milli-Ampere)
alpha = 0.987                  #common base current gain

#Calculation

IC = alpha * IE                #Collector current (in milli-Ampere)
IB = IE - IC                   #Base current (in milli-Ampere)

#Result

print "IC is ",IC," mA.\nIB is ",IB," mA."

IC is  9.87  mA.
IB is  0.13  mA.

Example 14.5 , Page Number 312

In [5]:
import math

#Variables

alpha1 = 0.975                  #common base current gain
beta1 = 200.0                   #common emitter current gain

#Calculation

beta = alpha1 / (1-alpha1)      #common emitter current gain           
alpha = beta1 / (beta1 + 1)     #common base current gain 

#Result

print "Value of beta when alpha = 0.975 is ",beta,".\nValue of alpha when beta = 200 is ",round(alpha,3),"."

Value of beta when alpha = 0.975 is  39.0 .
Value of alpha when beta = 200 is  0.995 .

Example 14.6 , Page Number 313

In [6]:
import math

#Variables

beta = 100.0                   #common emitter current gain
IC = 40.0                      #Collector current (in milli-Ampere)  

#Calculation

IB = IC / beta                 #Base current (in milli-Ampere)
IE = IB + IC                   #Emitter current (in milli-Ampere)

#Result

print "The value of emitter current is ",IE," mA."

The value of emitter current is  40.4  mA.

Example 14.7 , Page Number 313

In [7]:
import math

#Variables

beta = 150.0                   #common emitter current gain
IE = 10                        #Emitter current (in milli-Ampere)

#Calculation

alpha = beta / (beta + 1)      #common base current gain 
IC = alpha * IE                #Collector current (in milli-Ampere)
IB = IE - IC                   #Base current (in milli-Ampere)

#Result

print "Collector current is ",round(IC,2)," mA.\nBase current is ",round(IB,2)," mA."

Collector current is  9.93  mA.
Base current is  0.07  mA.

Example 14.8 , Page Number 313

In [8]:
import math

#Variables

beta = 170.0                   #common emitter current gain
IC = 80.0                      #Collector current (in milli-Ampere)  

#Calculation

IB = IC / beta                 #Base current (in milli-Ampere)
IE = IB + IC                   #Emitter current (in milli-Ampere)

#Result

print "Base current is ",round(IB,2)," mA.\nEmitter current is ",round(IE,2)," mA."

Base current is  0.47  mA.
Emitter current is  80.47  mA.

Example 14.9 , Page Number 314

In [9]:
import math

#Variables

IB = 0.125                       #Base current (in milli-Ampere)
beta = 200.0                     #common emitter current gain

#Calculation

IC = IB * beta                   #Collector current (in milli-Ampere)
IE = IC + IB                     #Emitter current (in milli-Ampere)

#Result

print "Value of collector current is ",IC," mA.\nValue of emitter current is ",IE," mA."

#Correction in book . The Value of IB is 0.125 mA.

Value of collector current is  25.0  mA.
Value of emitter current is  25.125  mA.

Example 14.10 , Page Number 314

In [10]:
import math

#Variables

IE = 12.0                        #Emitter current (in milli-Ampere)
beta = 140.0                     #common emitter current gain

#Calculation

IB = IE / (1 + beta)             #Base current (in milli-Ampere)
IC = IE - IB                     #Collector current (in milli-Ampere)

#Result

print "Collector current is ",round(IC,3)," mA.\nBase current is ",round(IB,3)," mA."

Collector current is  11.915  mA.
Base current is  0.085  mA.

Example 14.11 , Page Number 314

In [11]:
import math

#Variables

IB = 105 * 10**-3                 #Base current (in milli-Ampere)
IC = 2.05                         #Collector current (in milli-Ampere)

#Calculation

beta = IC / IB                    #Common base current gain
alpha = beta / (1 + beta)         #Common emitter current gain
IE = IB + IC                      #Emitter current (in milli-Ampere)
IC1 = IC + 0.65                   #New collector current (in milli-Ampere)
IB1 = IB + 27 * 10**-3            #New base current (in milli-Ampere)                     
beta1 = IC1 / IB1                 #New value of beta

#Result

print "Beta of the transistor is ",round(beta,1),".\nalpha of the transistor is ",round(alpha,2),".\nEmitter current is ",IE," mA.\nNew value of beta is ",round(beta1,2),"."

#Correction to be done in book in value of IB . IB is in micro - Ampere in both initial and in the changed condition. In calculation proper conversion has been done.

Beta of the transistor is  19.5 .
alpha of the transistor is  0.95 .
Emitter current is  2.155  mA.
New value of beta is  20.45 .

Example 14.12 , Page Number 317

In [12]:
import math

#Variables

alpha = 0.98                               #common base current gain
ICO = 5 * 10**-3                           #Leakage current (in milli-Ampere)
IB = 100 * 10**-3                          #Base current (in milli-Ampere)

#Calculation

IC = (alpha * IB + ICO)/ (1 - alpha)       #Collector current (in milli-Ampere)
IE = IC + IB                               #Emitter current (in milli-Ampere)                        

#Result

print "Value of collector current is ",IC," mA.\nValue of emitter current is ",IE," mA."

#Correction about conversion of micro-Ampere and milli-Ampere to be done in the book.

Value of collector current is  5.15  mA.
Value of emitter current is  5.25  mA.

Example 14.13 , Page Number 318

In [13]:
import math

#Variables

ICBO = 10 * 10**-3                    #Leakage current (in milli-Ampere)
beta = hFE = 50                       #common emitter current gain
T2 = 50.0                             #Temperature (in degree Celsius)  
T1 = 27.0                             #Temperature (in degree Celsius)

#Calculation

#Case (a)

IB = 0.25                             #Base current (in milli-Ampere)
IC = beta * IB + (1 + beta)* ICBO     #Value of new collector current (in milli-Ampere)

#Case (b)

ICBO1 = ICBO * 2**((T2 - T1)/10)      #ICBO at 50 degree celsius (in milli-Ampere)
IC1 =  beta * IB + (1 + beta)* ICBO1  #Value of new collector current (in milli-Ampere)

#Result

print "Collector current when IB = 0.25 mA is ",IC," mA.\nCollector current at 50 degree Celsius is ",round(IC1,2)," mA."

Collector current when IB = 0.25 mA is  13.01  mA.
Collector current at 50 degree Celsius is  15.01  mA.