Chapter 12 , PN Junction Diode¶
Example 12.1 , Page Number 226¶
In [5]:
import math
#Variables
I0 = 2 * 10**-7 #Current (in Ampere)
VF = 0.1 #Forward voltage (in volts)
#Calculation
I = I0 * (math.exp(40*VF)-1) #Current through diode (in Ampere)
#Result
print "Current throrough diode is ",round(I*10**6,2)," micro-Ampere."
Example 12.2 , Page Number 226¶
In [14]:
import math
#Variables
VF = 0.22 #Forward voltage (in volts)
T = 298.0 #Temperature (in kelvin)
I0 = 10**-3 #Current (in Ampere)
n = 1
#Calculation
VT = T/11600 #Volt equivalent of temperature (in volts)
I = I0*(exp(VF/(n*VT))-1) #Diode Current (in Ampere)
#Result
print "Diode current is ",round(I,1)," A."
Example 12.3 , Page Number 226¶
In [2]:
import math
#Variables
I1 = 0.5 * 10**-3 #Diode current1 (in Ampere)
V1 = 340 * 10**-3 #Voltage1 (in volts)
I2 = 15 * 10**-3 #Diode current2 (in Ampere)
V2 = 440 * 10**-3 #Voltage2 (in volts)
#Calculation
n = 4/math.log(30) #By solving both the given equations
#Result
print "Value of n is ",round(n,2),"."
Example 12.4 , Page Number 228¶
In [12]:
import math
#Variables
I300 = 10 * 10**-6 #Current at 300 kelvin (in Ampere)
T1 = 300 #Temperature (in kelvin)
T2 = 400 #Temperature (in kelvin)
#Calculation
I400 = I300 * 2**((T2-T1)/10) #Current at 400 kelvin (in Ampere)
#Result
print "Current at 400 k is ",round(I400*10**3,1)," mA."
Example 12.5 , Page Number 230¶
In [11]:
import math
#Variables
rb = 2 #bulk resistance (in ohm)
IF = 12 * 10**-3 #FOrward current (in Ampere)
#Calculation
VF = 0.6 + IF * rb #Voltage drop (in volts)
#Result
print "Voltage drop across a silicon diode is ",VF," V."
Example 12.6 , Page Number 230¶
In [10]:
import math
#Variables
T = 398.0 #Temperature (in kelvin)
I0 = 30 * 10**-6 #Reverse saturation current (in Ampere)
V = 0.2 #Voltage (in volts)
#Calculation
VT = T/11600 #Volt equivalent of temperature (in volts)
I = I0 * (math.exp(V/VT)-1) #Diode current (in Ampere)
rac = VT/I0 * math.exp(-V/VT) #dynamic resistance in forward direction (in ohm)
rac1 = VT/I0 * math.exp(V/VT) #dynamic resistance in reverse direction (in ohm)
#Result
print "Dynamic resistance in forward direction is ",round(rac,2)," ohm.\nDynamic resistance in backward direction is ",round(rac1/10**6,3)," Mega-ohm."
Example 12.8 , Page Number 237¶
In [9]:
import math
#Variables
PDmax = 0.5 #power dissipation (in watt)
VF = 1 #Forward voltage (in volts)
VBR = 150 #Breakdown voltage (in volts)
#Calculation
IFmax = PDmax/VF #Maximum forward current (in Ampere)
IR = PDmax/VBR #Breakdwon current that burns out the diode (in Ampere)
#Result
print "Maximum forward current is ",IFmax," A.\nBreakdwon current that burns out the diode is ",round(IR*10**3,2)," mA."
Example 12.9 , Page Number 238¶
In [8]:
import math
#Variables
R = 330 #Resistance (in ohm)
VS = 5 #Source voltage (in volts)
#Calculation
VD = VS #Voltage drop across diode (in volts)
VR = 0 #Voltage drop across the resistance (in volts)
I = 0 #Current through circuit
#Result
print "Voltage drop across the diode is ",VD," V.\nVoltage drop across the resistance is ",VR," V.\nCurrent through the circuit is ",I," A."
Example 12.10 , Page Number 239¶
In [7]:
import math
#Variables
VS = 12.0 #Source coltage (in volts)
R = 470.0 #Resistance (in ohm)
#Calculation
VD = 0 #Voltage drop across diode (in volts)
VR = VS #Value of VR (in volts)
I = VS/R #Current (in Ampere)
#Result
print "Value of VD is ",VD," V.\nValue of VR is ",VR," V.\nCurrent through the circuit is ",round(I*10**3,2)," mA."
Example 12.11 , Page Number 239¶
In [6]:
import math
#Variables
VS = 6 #Source voltage (in volts)
R1 = 330 #Resistance (in ohm)
R2 = 470 #Resistance (in ohm)
VD = 0.7 #Diode voltage (in volts)
#Calculation
RT = R1 + R2 #Total Resistance (in ohm)
I = (VS - 0.7)/RT #Current through the diode
#Result
print "Current through the circuit is ",I * 10**3," mA."
Example 12.12 , Page Number 240¶
In [5]:
import math
#Variables
VS = 5 #Source voltage (in volts)
R = 510 #Resistance (in ohm)
VF = 0.7 #Forward voltage drop (in volts)
#Calculation
VR = VS - VF #Net voltage (in volts)
I = VR / R #Current through the diode
#Result
print "Voltage across the resistor is ",VR," V.\nThe circuit current is ",round(I * 10**3,2)," mA."
Example 12.13 , Page Number 240¶
In [4]:
import math
#Variables
VS = 6 #Source voltage (in volts)
VD1 = VD2 = 0.7 #Diode Voltage drop (in volts)
R = 1.5 * 10**3 #Resistance (in ohm)
#Calculation
I = (VS - VD1 - VD2)/R #Current (in Ampere)
#Result
print "Total current through the circuit is ",round(I * 10**3,3)," mA."
Example 12.14 , Page Number 240¶
In [3]:
import math
#Variables
VS = 12 #Source voltage (in volts)
R1 = 1.5 * 10**3 #Resistance (in ohm)
R2 = 1.8 * 10**3 #Resistance (in ohm)
VD1 = VD2 = 0.7 #Diode Voltage drop (in volts)
#Calculation
RT = R1 + R2 #Total Resistance (in ohm)
I = (VS - VD1 - VD2)/RT #Current (in Ampere)
#Result
print "Total current through the circuit is ",round(I * 10**3,3)," mA."
Example 12.15 , Page Number 241¶
In [2]:
import math
#Variables
R = 3.3 * 10**3 #Resitance (in ohm)
#Calculation
#Case (a)
V11 = V21 = 0 #Voltages (in volts)
V01 = 0 #Output Voltage (in volts)
#Case (b)
V21 = 0 #Voltage (in volts)
V22 = 5 #Voltage (in volts)
V02 = V22 - 0.7 #Output voltage (in volts)
#Case (c)
V31 = 5 #Voltage (in volts)
V32 = 0 #Voltages (in volts)
V03 = V31 - 0.7 #Output voltage (in volts)
#Case (d)
V41 = V42 = 5 #Voltages (in volts)
V04 = V41 - 0.7 #Output voltage (in volts)
#Result
print "Output Voltage in case 1 is ",V01," V.\nOutput Voltage in case 2 is ",V02," V.\nOutput Voltage in case 3 is ",V03," V.\nOutput Voltage in case 4 is ",V04," V."
Example 12.16 , Page Number 242¶
In [2]:
import math
import numpy
%matplotlib inline
from matplotlib.pyplot import plot,title,xlabel,ylabel
#Variables
rB = 1.0 #bulk resistance (in ohm)
V = 10 * 10**-3 #Signal Amplitude (in volts)
#Calculation
#Case (a)
R = 20.0 #Resitance (in kilo-ohm)
Vg = 20.0 #Source voltage (in volts)
I = (Vg - 0.7)/R #Current (in milli-Ampere)
#Case (b)
rj = 50.0 #junction resistance (in ohm)
re = rB + rj #a.c. resistance (n ohm)
rnet = re * (R*10**3)/(re + (R*10**3)) #Net resistance (in ohm)
V1 = V * re/(re + 1000) #Voltage drop across 51 ohm resitance (in ohm)
#Result
print "Current in dc circuit is ",round(I)," mA.\na.c voltage drop across 51 ohm resistance is ",round(V1*10**3,3)," mV."
#Graph
x = numpy.linspace(-4*math.pi,4*math.pi,500)
y = numpy.sin(x)
plot(x,0.7 + 0.48*10**-3*y)
title("Total Voltage 'V' across the diode")
xlabel("t(in seconds)->")
ylabel("Voltage(in volts)->")
Out[2]:
