Chapter 22 , BJT Biasing and Stabilization¶
Example 22.1 , Page Number 527¶
In [1]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel
#Variables
VBB = 10.0 #Base Voltage (in volts)
RB = 47.0 #Base Resistance (in kilo-ohm)
VCC = 20.0 #Voltage Source (in volts)
RC = 10.0 #Collector Resistance (in kilo-ohm)
beta = 100.0 #Common-Emitter current gain
#Calculation
ICsat = VCC / RC #Saturation current (in milli-Ampere)
VCEcutoff = VCC #Cutoff voltage (in volts)
#Result
print "The value of saturation current is ",ICsat," mA.\nThe value of cut-off voltage is ",VCEcutoff," V."
#Graph
x = numpy.linspace(0,20,100)
plot(x,x/10)
title("d.c. load line")
xlabel("Collector-to-emitter voltage VCE (V)")
ylabel("Collector current IC (mA)")
Out[1]:
Example 22.2 , Page Number 528¶
In [2]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel,annotate
#Variables
VCC = 20.0 #Source voltage (in volts)
RC = 300.0 #Collector resistance (in ohm)
VBB = 10.0 #Base voltage (in volts)
RB = 50.0 #Base Resistance (in kilo-ohm)
beta = 200.0 #Common-emittter current gain
#Calculation
ICsat = VCC / RC #Saturation current (in Ampere)
VCEcutoff = VCC #Cutoff voltage (in volts)
#Using kirchoff's voltage law
IB = (VBB - 0.7) / RB #Base current (in milli-Ampere)
IC = beta * IB #Collector current (in milli-Ampere)
VCE = VCC - IC * RC * 10**-3 #Collector-to-emitter voltage (in volts)
#Result
print "Q-points corresponds to ",VCE," V and ",IC," mA."
#Graph
x = numpy.linspace(0,20,100)
plot(x,66.7 - 66.7/20 * x)
title("d.c. load line")
xlabel("Collector-to-emitter voltage VCE (V)")
ylabel("Collector current IC (mA)")
annotate("Q",xy=(8.84,37.2))
annotate("66.7",xy=(0,66.7))
annotate("37.2",xy=(0,37.2))
annotate("8.84",xy=(8.84,0))
Out[2]:
Example 22.3 , Page Number 533¶
In [3]:
import math
#Variables
VCC = 25.0 #Source voltage (in volts)
RC = 820.0 #Collector Resistance (in ohm)
RB = 180.0 #Base Resistance (in kilo-ohm)
beta = 80.0 #Common-Emitter current gain
#Calculation
IB = VCC / RB #Base current (in milli-Ampere)
IC = beta * IB #Collector current (in milli-Ampere)
VCE = VCC - IC * RC * 10**-3 #Collector-to-Emitter voltage (in volts)
#Result
print "The value of base current is ",round(IB,2)," mA.\nThe value of Collector current is ",round(IC,2)," mA.\nTHe value of Collector-to-Emitter voltage is ",round(VCE,2)," V."
#Slight variation in answers due to higher precision.
Example 22.4 , Page Number 534¶
In [4]:
#Variables
VBB = 2.7 #Base voltage (in Volts)
RB = 40.0 #Base resistance (in kilo-ohm)
VCC = 10.0 #Supply voltage (in volts)
RC = 2.5 #Collector resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-base voltage (in volts)
beta = 100.0 #Current gain
#Calculation
IB = (VBB - VBE)/RB #Base current (in milli-Ampere)
IC = beta * IB
#Result
print "The base current is ",IB," mA."
print "The collector current is ",IC," mA."
Example 22.5 , Page Number 534¶
In [5]:
import math
#Variables
VCC = 5.0 #Source voltage (in volts)
RC = 5.0 #Collector resistance (in kilo-ohm)
VBB = 5.0 #Base voltage (in volts)
RB = 100.0 #Base Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
beta = 30.0 #Common-Emitter current gain
#Calculation
IB = (VBB - VBE)/RB #Base Current (in milli-Ampere)
IC = beta * IB #Collector Current (in milli-Ampere)
IC1 = VCC / RC #Collector Current (in milli-Ampere)
#Result
print "The value of collector current is for operation in saturation region is ",IC1," mA.\nSince ",IC," mA is greater than ",IC1," mA , therefore it will operate in saturation region."
Example 22.6 , Page Number 535¶
In [6]:
import math
#Variables
VCC = 12.0 #Source voltage (in volts)
RC = 330.0 #Collector resistance (in ohm)
IB = 0.3 #Base current (in milli-Ampere)
beta = 100.0 #Common-emitter current gain
#Calculation
RB = VCC / IB #Resistance (in kilo-ohm)
S = 1 + beta #Stability factor
IC = beta * IB #Collector current (in milli-Ampere)
VCE = VCC - IC * RC * 10**-3 #Collector-Ground voltage (in volts)
#Result
print "Stability factor for the fixed bias circuit is ",S,".\nThe voltage between the collector and the ground is ",VCE," V."
Example 22.7 , Page Number 536¶
In [7]:
import math
#Variables
VCC = 20.0 #Source voltage (in volts)
RC = 2.0 #Collector resistance (in kilo-ohm)
RB = 400.0 #Base Resistance (in kilo-ohm)
beta = 100.0 #Common-Emitter current gain
RE = 1.0 #Emitter Resistance (in kilo-ohm)
#Calculation
IB = VCC / (RB + beta * RE) #Base current (in milli-Ampere)
IC = beta * IB #Collector Current (in milli-Ampere)
VCE = VCC - IC * (RC + RE) #Collector-to-Emitter Voltage (volts)
#Result
print "VCE of the transistor is ",VCE," V.\nVCC of the transistor is ",VCC," V.\nIB of the transistor is ",IB," mA.\nIC of transistor is ",IC," mA."
Example 22.8 , Page Number 537¶
In [3]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel,annotate
#Variables
VCC = 12.0 #Source voltage (in volts)
RC = 2.2 #Collector resistance (in kilo-ohm)
RB = 240.0 #Base Resistance (in kilo-ohm)
beta = 50.0 #Common-Emitter current gain
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
RE = 0 #Emitter resistance (in kilo-ohm)
#Calculation
IC = (VCC - VBE)/(RE + RB/beta) #Collector current (in milli-Ampere)
VCE = VCC - IC * RC #Collector-to-Emitter voltage (in volts)
ICsat = VCC / RC #Saturation current (in milli-Ampere)
VCEcutoff = VCC #Cut-off voltage (in volts)
#Result
print "The value of IC is ",round(IC,2)," mA.\nThe value of VCE is ",VCEcutoff," V."
#Graph
x = numpy.linspace(0,12,100)
plot(x,5.45 - 5.45/12 * x)
title("d.c. load line")
xlabel("Collector-to-emitter voltage VCE (V)")
ylabel("Collector current IC (mA)")
annotate("6.83 V",xy=(6.83,0))
annotate("5.45 mA",xy=(0,5.45))
Out[3]:
Example 22.9 , Page Number 538¶
In [4]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel,annotate
#Variables
VCC = 30.0 #Source voltage (in volts)
RC = 5.0 #Collector resistance (in kilo-ohm)
RB = 1.5 * 10**3 #Base Resistance (in kilo-ohm)
beta = 100.0 #Common-emitter current gain
#Calculation
ICsat = VCC / RC #Saturation current (in milli-Ampere)
VCEcutoff = VCC #Cut-off voltage (in volts)
IB = VCC / RB #Base current (in milli-Ampere)
IC = beta * IB #Collector current (in milli-Ampere)
VCE = VCC - IC * RC #Collector-to-Emitter voltage (in volts)
#Result
print "Operating voltage is ",VCE," V.\nOpearing current is ",IC," mA."
#Graph
x = numpy.linspace(0,30,100)
plot(x,6.0 - 6.0/30.0 * x)
title("d.c. load line")
xlabel("Collector-to-emitter voltage VCE (V)")
ylabel("Collector current IC (mA)")
annotate("20 V",xy=(20,0))
annotate("2 mA",xy=(0,2))
annotate("Q",xy=(20,2))
Out[4]:
Example 22.10 , Page Number 538¶
In [10]:
import math
#Variables
VCC = 5.0 #Source voltage (in volts)
RE = 100.0 #Emitter resistance (in kilo-ohm)
VBE = 0.7 #Emitter-base Voltage (in volts)
#Calculation
#Case 1 : when VBB = 0.2 V ->OFF
#Case 2: when VBB = 3 V ->ON
#Result
print "When VBB = 0 V , LED is in OFF condition.\nWhen VBB = 3 V , LED is in ON condition."
Example 22.11 , Page Number 539¶
In [11]:
import math
#Variables
VCC = 25.0 #Source voltage (in volts)
RC = 820.0 #Collector resistance (in ohm)
RB = 180.0 * 10**3 #Base Resistance (in ohm)
beta = 80.0 #Common-Emitter current gain
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
RE = 200.0 #Emitter resistance (in kilo-ohm)
#Calculation
IC = (VCC -VBE)/(RE + RB / beta) #Collector current (in milli-Ampere)
VCE = VCC - IC * RC #Collector-to-Emitter voltage (in volts)
S = 1 + beta #Stability factor
#Result
print "Collector current is ",round(IC * 10**3,1)," mA.\nCollector-to-Emitter voltage is ",VCE," V.\nStability factor is ",S,"."
#Stability is not calculated in the book.
Example 22.12 , Page Number 540¶
In [5]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel,annotate
#Variables
VCC = 10.0 #Source voltage (in volts)
RC = 10.0 * 10**3 #Collector resistance (in ohm)
RB = 100.0 * 10**3 #Base Resistance (in ohm)
beta = 100.0 #Common-Emitter current gain
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
IC = (VCC -VBE)/(RC + RB / beta) #Collector current (in Ampere)
VCE = VCC - IC * RC #Collector-to-Emitter voltage (in volts)
ICsat = VCC / RC #Saturation current (in milli-Ampere)
VCEcutoff = VCC #Cut-off voltage (in volts)
#Result
print "Collector current is ",round(IC * 10**3,3)," mA.\nCollector-to-Emitter voltage is ",round(VCE,2)," V."
#Graph
x = numpy.linspace(0,10,100)
plot(x,6.0 - 6.0/30.0 * x)
title("d.c. load line")
xlabel("Collector-to-emitter voltage VCE (V)")
ylabel("Collector current IC (mA)")
annotate("20 V",xy=(20,0))
annotate("2 mA",xy=(0,2))
annotate("Q",xy=(20,2))
Out[5]:
Example 22.13 , Page Number 541¶
In [13]:
import math
#Variables
VCC = 10.0 #Source voltage (in volts)
RC = 2.0 * 10**3 #Collector resistance (in ohm)
RB = 100.0 * 10**3 #Base Resistance (in ohm)
beta = 50.0 #Common-Emitter current gain
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
IB = (VCC - VBE)/(RB + beta * RC) #Base current (in Ampere)
IC = beta * IB #Collector current (in Ampere)
IE = IC #Emitter current (in Ampere)
S = 1 + beta #Stability factor
#Result
print "IB is ",IB * 10**3," mA.\nIC is ",IC * 10**3," mA.\nIE is ",IE * 10**3," mA."
Example 22.14 , Page Number 542¶
In [14]:
import math
#Variables
#When VC = 0 volts
VCC = 9.0 #Source voltage (in volts)
RB = 220.0 #Base Resistance (in kilo-ohm)
RC = 3.3 #Collector Resistance (in kilo-ohm)
VBE = 0.3 #Emitter-to-Base voltage (in volts)
beta = 100.0 #Common emitter current gain
#Calculation
IB = (VCC - VBE)/((RB + beta*RC)* 10**3) #Base current (in Ampere)
IC = beta * IB #Collector current (in Ampere)
VCE = VCC - IC * RC * 10**3 #Collector-to-emitter voltage (in volts)
VC = VCE #Collector voltage (in volts)
ICRC = VCC #Voltage (in volts)
#When VC = 9 volts
IB1 = 16.0 #Base current (in micro-Ampere)
IC1 = beta * IB1 #Collector current (in micro-Ampere)
RC1 = 0 #Collector Resistance (in ohm)
#Result
print "In case 1, Collector junction is short circuited.\nIn case 2, Collector resistance is short circuited. "
Example 22.15 , Page Number 542¶
In [15]:
import math
#Variables
VCC = 12.0 #Source voltage (in volts)
RE = 100.0 #Emitter Resistance (in ohm)
RC = 3.3 #Collector Resistance (in kilo-ohm)
IE = 2.0 #Emitter current (in milli-Ampere)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
alpha = 0.98 #Common base current gain
R2 = 20.0 #Resistance (in kilo-ohm)
#Calculation
IC = alpha * IE #Collector current (in milli-Ampere)
VB = VBE + IE * RE * 10**-3 #Base voltage (in volts)
VC = VCC - IC * RC #Collector voltage (in volts)
IR2 = VC / (R2) #Current through resistance 2 (in milli-Ampere)
IB = IE - IC #Base current (in milli-Ampere)
IR1 = IR2 + IB #Current through resistance 1 (in milli-Ampere)
R1 = (VC - VB) / IR1 #Value of the resistance (in kilo-ohm)
#Result
print "The value of R1 is ",round(R1,1)," kilo-ohm."
#Correction to be done in the book about the formula of IR2
Example 22.16 , Page Number 543¶
In [2]:
import math
#Variables
VCC = 24.0 #Source voltage (in volts)
RE = 270.0 #Emitter Resistance (in ohm)
RC = 10.0 #Collector Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
beta = 45.0 #Common emitter current gain
VCE = 5.0 #Collector-to-Emitter voltage (in volts)
#Calculation
IC = (VCC - VCE) / RC #Collector current (in milli-Ampere)
RB = ((VCC - VBE) / IC - RC) * beta #Base Resistance (in kilo-ohm)
#Result
print "Base resistance is ",round(RB,2)," kilo-ohm."
#Calculation mistake in book.
Example 22.17 , Page Number 545¶
In [1]:
import math
#Variables
VCC = 3.0 #Source voltage (in volts)
RB = 33.0 #Base Resistance (in kilo-ohm)
RC = 1.8 #Collector Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
beta = 90.0 #Common emitter current gain
#Calculation
IB = (VCC - VBE) / (RB + beta * RC) #Base current (in milli-Ampere)
IC = beta * IB #Collector current (in milli-Ampere)
VCE = VCC -IC * RC #Collector-to-emitter voltage (in volts)
S = (1 + beta)/(1 + beta*RC/(RC + RB)) #Stability factor
#Result
print "DC bias current is ",round(IC,2)," mA.\nDC bias voltage is ",round(VCE,1)," V.\nStability factor is ",round(S,1),"."
Example 22.18 , Page Number 546¶
In [2]:
import math
#Variables
VCC = 10.0 #Source voltage (in volts)
RE = 500.0 #Emitter Resistance (in ohm)
RC = 1.0 #Collector Resistance (in kilo-ohm)
R1 = 10.0 #Resistance (in kilo-ohm)
R2 = 5.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
beta = 100.0 #Common emitter current gain
#Calculation
VB = VCC * (R2 /(R1 + R2)) #Base voltage (in volts)
VE = VB - VBE #Emitter voltage (in volts)
IE = VE / RE #Emitter current (in Ampere)
IC = IE #Collector current (in Ampere)
VCE = VCC - IC * (RC * 10**3 + RE) #Collector-to-Emitter voltage (in volts)
#Result
print "Collector current is ",round(IC * 10**3,2)," mA.\nCollector-to-Emitter voltage is ",VCE," V."
Example 22.19 , Page Number 547¶
In [3]:
import math
#Variables
VCC = 15.0 #Source voltage (in volts)
RE = 2.0 #Emitter Resistance (in kilo-ohm)
RC = 1.0 #Collector Resistance (in kilo-ohm)
R1 = 10.0 #Resistance (in kilo-ohm)
R2 = 5.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
Vth = VCC * (R2 /(R1 + R2)) #Thevenin's voltage (in volts)
Rth = R1 * R2 / (R1 + R2) #Thevenin's equivalent resistance (in kilo-ohm)
IE = (Vth - VBE)/(RE) #Emitter current (in milli-Ampere)
VCE = VCC - IE * (RC + RE) #Collector-to-Emitter voltage (in volts)
#Result
print "Emitter current is ",IE," mA.\nThe value of collector-to-emitter voltage is ",VCE," V."
Example 22.20 , Page Number 549¶
In [4]:
import math
#Variables
VCC = 12.0 #Source voltage (in volts)
RE = 100.0 #Emitter Resistance (in ohm)
RC = 1.0 #Collector Resistance (in kilo-ohm)
R1 = 25.0 #Resistance (in kilo-ohm)
R2 = 5.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
betamin = 50.0 #Common emitter current gain (min)
betamax = 150.0 #Common emitter current gain (max)
#Calculation
Vth = VCC * (R2 /(R1 + R2)) #Thevenin's voltage (in volts)
Rth = R1 * R2 / (R1 + R2) * 10**3 #Thevenin's equivalent resistance (in ohm)
IE1 = (Vth - VBE)/(RE + Rth/betamin) #Emitter current (in Ampere)
IE2 = (Vth - VBE)/(RE + Rth/betamax) #Emitter current (in Ampere)
perc_change = (IE2 - IE1) / IE1 * 100 #Percentage change in the value of beta
#Result
print "The percentage change in collector current is ",round(perc_change,1)," %."
Example 22.21 , Page Number 549¶
In [5]:
import math
#Variables
VCC = 9.0 #Source voltage (in volts)
RE = 680.0 #Emitter Resistance (in ohm)
RC = 1.0 #Collector Resistance (in kilo-ohm)
R1 = 33.0 #Resistance (in kilo-ohm)
R2 = 15.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
VB = VCC * R2 / (R1 + R2) #Base voltage (in volts)
VE = VB - VBE #Emitter voltage (in volts)
IE = VE / RE #Emitter current (in Ampere)
IC = IE #Collector current (in Ampere)
VRC = IC * RC * 10**3 #Voltage across collector resistance (in volts)
VC = VCC - VRC #Collector voltage (in volts)
VCE = VC - VE #Collector-to-emitter voltage (in volts)
#Result
print "Operating point values are IC = ",round(IC * 10**3,1)," mA and VCE = ",round(VCE,3)," V."
Example 22.22 , Page Number 550¶
In [6]:
import math
#Variables
VCC = 5.0 #Source voltage (in volts)
RE = 0.3 #Emitter Resistance (in kilo-ohm)
IC = 1.0 #Collector Current (in milli-Ampere)
beta = 100.0 #Common emitter current gain
VCE = 2.5 #Collector-to-Emitter voltage (in volts)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
ICO = 0 #Reverse saturation current (in Ampere)
R2 = 10.0 #Resistance (in kilo-ohm)
#Calculation
IE = IC #Emitter current (in milli-Ampere)
RC = (VCC - VCE) / IE - RE #Collector resistance (in kilo-ohm)
VE = IE * RE #Emitter voltage (in volts)
VB = VE + VBE #Base voltage (in volts)
R1 = VCC / VB * R2 - R2 #Resistance1 (in kilo-ohm)
#Result
print "The value of R1 is ",R1," kilo-ohm and value of RC is ",RC * 10**3," ohm."
Example 22.23 , Page Number 551¶
In [7]:
import math
#Variables
VCC = 20.0 #Source voltage (in volts)
RE = 5.0 #Emitter Resistance (in kilo-ohm)
RC = 1.0 #Collector Resistance (in kilo-ohm)
R1 = 10.0 #Resistance (in kilo-ohm)
R2 = 10.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
VB = VCC * R2 / (R1 + R2) #Voltage (in volts)
VE = VB - VBE #Emitter voltage (in volts)
IE = VE / RE #Emitter current (in milli-Ampere)
IC = IE #Collector current (in milli-Ampere)
VCE = VCC - IC * RC #Collector-to-emitter voltage (in volts)
VC = VCE + VE #Collector potential (in volts)
#Result
print "Emitter current is ",IE," mA.\nValue of VCE is ",VCE," V.\nValue of collector potential is ",VC," V."
#VC is not calculated in the book.
Example 22.24 , Page Number 552¶
In [8]:
import math
#Variables
VCC = 8.0 #Source voltage (in volts)
VRC = 0.5 #Voltage across collector resistance (in volts)
RC = 800.0 #Collector resistance (in ohm)
alpha = 0.96 #common base current gain
#Calculation
VCE = VCC - VRC #Collector-to-emitter voltage (in volts)
IC = VRC / RC #Collector current (in milli-Ampere)
IE = IC / alpha #Emitter current (in milli-Ampere)
IB = IE - IC #Base current (in milli-Ampere)
#Result
print "Collector-to-Emitter VCE is ",VCE," V.\nBase current is ",round(IB * 10**3,3)," mA."
Example 22.27 , Page Number 554¶
In [9]:
import math
#Variables
beta = 50.0 #Common emitter current gain
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
VCC = 22.5 #Source voltage (in volts)
RC = 5.6 #Collector Resistance (in kilo-ohm)
VCE = 12.0 #Collector-to-emitter voltage (in volts)
IC = 1.5 #Collector current (in milli-Ampere)
#Stability factor (S) <= 3.
S = 3
#Calculation
RE = (VCC - VCE)/IC - RC #Emitter resistance (in kilo-ohm)
Rth = (4375 - (1.4 * 10**3))*10**-3 #Thevenin's Equivalent Resistance (in ohm)
R2 = 0.1 * beta * RE #Resistance (in kilo-ohm)
R1 = (R2 - Rth)**-1 * R2 *Rth #Resistance 1 (in kilo-ohm)
#Result
print "Value of RE is ",RE ," kilo-ohm.\nValue of R1 is ",round(R1,1)," kilo-ohm.\nValue of R2 is ",R2," kilo-ohm."
Example 22.28 , Page Number 556¶
In [10]:
import math
#Variables
VEE = 10.0 #Emitter Bias Voltage (in volts)
VCC = 10.0 #Source voltage (in volts)
RC = 1.0 #Collector Resistance (in kilo-ohm)
RE = 5.0 #Emitter Resistance (in kilo-ohm)
RB = 50.0 #Base Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
#Calculation
VE = -VBE #Emitter voltage (in volts)
IE = (VEE - VBE)/ RE #Emitter current (in milli-Ampere)
IC = IE #Collector current (in milli-Ampere)
VC = VCC - IC * RC #Collector voltage (in volts)
VCE = VC - VE #Collector-to-Emitter voltage (in volts)
#Result
print "The value of emitter current is ",IE," mA.\nTHe value of collector current is ",IC," mA.\nThe value of collector-to-emitter voltage is ",VCE," V."
Example 22.29 , Page Number 557¶
In [12]:
import math
#Variables
VEE = 20.0 #Emitter Bias Voltage (in volts)
VCC = 20.0 #Source voltage (in volts)
RC = 5.0 #Collector Resistance (in kilo-ohm)
RE = 10.0 #Emitter Resistance (in kilo-ohm)
RB = 10.0 #Base Resistance (in kilo-ohm)
VE = -0.7 #Emitter Voltage (in volts)
betamin = 50.0 #Common emitter current gain minimum
betamax = 100.0 #Common emitter current gain maximum
VE1 = -0.6 #Emitter Voltage1 (in volts)
VBE = 0.7 #Emitter-to-base voltage (in volts)
VBE1 = 0.6 #New emitter-to-base voltage (in volts)
#Calculation
IE = (VEE - VBE)/(RE + RB / betamin) #Emitter current (in milli-Ampere)
IC = IE #Collector current (in milli-Ampere)
VC = VCC - IC * RC #Collector voltage (in volts)
VCE = VC - VE #Collector-to-emitter voltage (in volts)
IE1 = (VEE - VBE1)/(RE + RB/betamax) #Emitter current 1 (in milli-Ampere)
IC1 = IE1 #Collector current 1 (in milli-Ampere)
VC1 = VCC - IC1 * RC #Collector voltage 1 (in volts)
VCE1 = VC1 - VE1 #Collector-to-emitter voltage 1 (in volts)
dIC = (IC1 - IC) / IC #Change in collector current
dVCE = (VCE - VCE1) / VCE #Change in collector to emitter voltage
#Result
print "The change is collector current is ",round(dIC,5)* 100,"%.\nThe change in collector to emitter voltage is ",100*round(dVCE,4),"%."
#Slight changes due to higher precision.
Example 22.30 , Page Number 561¶
In [13]:
import math
#Variables
VCC = 12.0 #Source voltage (in volts)
RE = 1.0 #Emitter Resistance (in kilo-ohm)
RC = 2.0 #Collector Resistance (in kilo-ohm)
R1 = 100.0 #Resistance (in kilo-ohm)
R2 = 20.0 #Resistance (in kilo-ohm)
VBE = -0.2 #Emitter-to-Base Voltage (in volts)
beta = 100.0 #Common emitter current gain
#Calculation
VB = -VCC * R2 / (R1 + R2) #Base voltage (in volts)
VE = VB - VBE #Emitter voltage (in volts)
IE = -VE / RE #Emitter current (in milli-Ampere)
IC = IE #Collector current (in milli-Ampere)
VC = -(VCC - IC * RC) #Collector voltage (in volts)
VCE = VC - VE #Collector-to-emitter voltage (in volts)
#Result
print "Base voltage is ",VB," V.\nEmitter voltage is ",VE," V.\nCollector voltage is ",VC," V.\nCollector current is ",IC," mA.\nEmitter current is ",IE," mA.\nCollector-to-emitter voltage is ",VCE," V."
#Formula of IE and VB is given wrong in the book.
Example 22.31 , Page Number 561¶
In [14]:
import math
#Variables
VCC = 10.0 #Source voltage (in volts)
RE = 2.0 #Emitter Resistance (in kilo-ohm)
RC = 10.0 #Collector Resistance (in kilo-ohm)
R1 = 16.0 #Resistance (in kilo-ohm)
R2 = 4.0 #Resistance (in kilo-ohm)
VBE = 0.7 #Emitter-to-Base Voltage (in volts)
beta = 100.0 #Common emitter current gain
#Calculation
VB = VCC * R2 / (R1 + R2) #Base voltage (in volts)
VE = VB - VBE #Emitter voltage (in volts)
#Result
print "The value of base voltage is ",VB," V.\nThe value of emitter voltage is ",VE," V."
Example 22.32 , Page Number 562¶
In [15]:
import math
#Variables
VCC = 4.5 #Source voltage (in volts)
RE = 0.27 #Emitter Resistance (in kilo-ohm)
RC = 1.5 #Collector Resistance (in kilo-ohm)
R1 = 27.0 #Resistance (in kilo-ohm)
R2 = 2.7 #Resistance (in kilo-ohm)
VBE = 0.3 #Emitter-to-Base Voltage for germanium (in volts)
beta = 44.0 #Common emitter current gain
#Calculation
VB = - VCC * R2 / (R1 + R2) #Base voltage (in volts)
VE = VB - (-VBE) #Emitter voltage (in volts)
IE = VE / RE #Emitter current (in milli-Ampere)
IC = IE #Collector current (in milli-Ampere)
VRC = -IC * RC #Voltage across collector resistance (in volts)
VC = -(VCC - VRC) #Collector voltage (in volts)
VCE = -(-VC - (-VE)) #Collector-to-emitter voltage (in volts)
#Result
print "The operating point values are IC = ",round(-IC,3)," mA and VCE = ",round(VCE,2)," V."