# Chapter 02 : Semiconductor diodes¶

## Example 2.1, Page No 37¶

In [14]:
import math
#initialisation of variables
If=100*10**-3
Vf=.75      #given
print("a)")
print("forward resistance")

#Calculations
Rf=Vf/If
print("forward resistnace is %3.1fohm " %Rf)
print("b)")
Vr=50
Ir=100*10**-9
Rr=(Vr/Ir)

#Results
print("reverse resistnace is %.1fohm " %(Rr/10**6))

a)
forward resistance
forward resistnace is 7.5ohm
b)
reverse resistnace is 500.0ohm


## Example 2.2, Page No 39¶

In [15]:
import math
#initialisation of variables
If=70*10**-3

#Calculations
rd=(26*10**-3)/If
print("dynamic resistance is %.2fohm " %rd)
If=60*10**-3
Vf=.025
rd=Vf/If

#Results
print("dynamic resistance is %.2fohm " %rd)

dynamic resistance is 0.37ohm
dynamic resistance is 0.42ohm


## Example 2.3 Page No 40¶

In [16]:
import math
#initialisation of variables
R1=4.7*10**3
E=15.0
Vf=0.7

#Calculations
print("diode current is E=If*R1+Vf")
If=((E-Vf)/R1)*10**3

#Results
print(" diode current is %.2fmA " %If)

diode current is E=If*R1+Vf
diode current is 3.04mA


## Example 2.5, Page No 41¶

In [17]:
import math
#initialisation of variables
E=1.5
Vf=0.7
R1=10
rd=.25

#Calculations
print("a)")
If=(E-Vf)/R1
print(" forward current is %0.1fmA " %(If*1000))
print("b)")
If=(E-Vf)/(R1+rd)

#Results
print(" forward current is %0.1fmA " %(If*1000))

a)
forward current is 80.0mA
b)
forward current is 78.0mA


## Example 2.6 Page No 43¶

In [18]:
import math
#initialisation of variables
If=0
Vf=5.0
R1=100.0

#Calculations
E=(If*R1)+Vf
print("B)")
Vf=0
E=5.0
R1=100.0
If=(E/R1)*1000

#Results
print("resistance is %dmA " %If)

B)
resistance is 50mA


## Example 2.8 Page No 45¶

In [19]:
import math
#initialisation of variables
If=50*10**-3
Vf=1.1
R1=100.0

#Calculations
Vf1=If*R1
E=Vf1+Vf

#Results
print(" new supply voltage is %.2fV " %E)

 new supply voltage is 6.10V


## Example 2.9, Page No 48¶

In [20]:
import math
#initialisation of variables
P1=700.0*10**-3
Vf=0.7

#Calculations
If=P1/Vf
#at 65C
D=5*10**-3
T=65-25
P2=P1-D*T
If=P2/Vf

#Results
print( "maximum forward current at 65C is %.1fA " %(If*1000))

maximum forward current at 65C is 714.3A


## Example 2.10 Page No 49¶

In [21]:
import math
#initialisation of variables

Vf1=0.7
Vf=-1.8*10**-3
If=26.0*10**-3
T=100-25

#Calculations
Vf2=Vf1+(T*Vf)
print(" voltage at 100C is %.3f V " %Vf2)
print("At 25C")
T1=25.0
rd=(26*10**-3/If)*((T1+273)/298)
print(" resistance at 25 C is %.2f ohm " %rd)
print(" At 100C")
T2=100.0
rd=(26*10**-3/If)*((T2+273)/298)

#Results
print(" resistance at 100 C is %.2fohm " %rd)

 voltage at 100C is 0.565 V
At 25C
resistance at 25 C is 1.00 ohm
At 100C
resistance at 100 C is 1.25ohm


## Example 2.11 Page No 51¶

In [22]:
import math
#initialisation of variablesV_s=230
If=10*10**-3
Vf=0.7

#Calculations
t=70.0*10**-9
Cd=((t*If)/Vf)*10**9

#Results
print(" diffusion capacitance is %.2f nF " %Cd)

 diffusion capacitance is 1.00 nF


## Example 2.12 Page No 53¶

In [23]:
import math
#initialisation of variables
print("A")
trr=10.0*10**-9

#Calculations
tf=10.0*trr*10**9
print("minimum fall times is %d ns " %tf)
print("B)")
trr=3.0
tf=10*trr

#Results
print("minimum fall times is %d ns " %tf)

A
minimum fall times is 100 ns
B)
minimum fall times is 30 ns


## Example 2.14, Page No 58¶

In [24]:
import math
#initialisation of variables

Io=75.0*10**-3
#vertical scale of 5mA/cm

#Calculations
If=Io/5*10**-3
R1=15/(75*10**-3)
P=((Io)**2)*R1

#Results
print("Pr1 = %1.1f W  " %P)

Pr1 = 1.1 W


## Example 2.15, Page No 63¶

In [25]:
import math
#initialisation of variables
Vz=7.5
Pd=400.0*10**-3
D=3.2*10**-3

#Calculations
Izm=Pd/Vz
print("current at 50C is %.1fA " %(Izm*1000))
print("At 100C")
P2=Pd-((100-50)*D)
print(" power at 100C is %.3fW " %P2)
Izm=P2/Vz

#Results
print(" current at 100C is %.1fA " %(Izm*1000))

current at 50C is 53.3A
At 100C
power at 100C is 0.240W
current at 100C is 32.0A


## Example 2.16, Page No 64¶

In [26]:
import math
#initialisation of variables
E=20.0
R1=620.0
Vz=7.5

#Calculations
Vr1=E-Vz
Iz=Vr1/R1
print(" diode current is %.1f mA " %(Iz*1000))
Pd=Vz*Iz

#Results
print( "power dissipation is %.1f mW " %(Pd*1000))

 diode current is 20.2 mA
power dissipation is 151.2 mW