# Chapter 5: Junction Properties (Continued)¶

### Example 5.1 Page No 191¶

In [11]:
import math
ND=10**17           #in atoms/cm**3
NA=0.5*10**16       #in atoms/cm**3
Vo=0.7              #in Volts
V=-10.0               #in Volts
ND=ND*10**6         #in atoms/m**3
NA=NA*10**6         #in atoms/m**3
epsilon=8.85*10**-11  #in F/m
e=1.6*10**-19         #coulamb

VB=0.7               #in Volts
W1=math.sqrt(2*epsilon*VB*(1/NA+1/ND)/e)         #in m

VB=Vo-V              #in Volts
W2=math.sqrt(2*epsilon*VB*(1/NA+1/ND)/e)    #in m

print "When no external voltage is applied, Junction width is ",round(W1,8),"m"
print"When external voltage of -10 Volt is applied, Junction width is ",round(W2,7),"m"

When no external voltage is applied, Junction width is  3.9e-07 m
When external voltage of -10 Volt is applied, Junction width is  1.5e-06 m


### Example 5.3 Page No 195¶

In [17]:
CTzero=50            #in pF
VR=8                 #in Volt
VK=0.7               #in Volt
n=1/3.0                #for Si

CT=CTzero/((1+VR/VK)**n)   #in pF

print"Junction capacitance is",round(CT,2),"pF"

Junction capacitance is 21.59 pF


### Example 5.4 Page No.196¶

In [22]:
L=12.5*10**-3          #mH inductance
C1=4.0                 #pF Capacitance
C2=40.0                #pF Capacitance

Ctmin=(C1*C1)/(C1+C1)     #Min value of total Capacitance
Ctmax=(C2*C2)/(C2+C2)     #Max value of total Capacitance
Fmax=1/(2*math.pi*math.sqrt(L*Ctmin*10**-12))
Fmin=1/(2*math.pi*math.sqrt(L*Ctmax*10**-12))

print"The tuning range of circuit lies between",round(Fmin/1000,2),"khz and",round(Fmax/1000,0),"Mhz"

The tuning range of circuit lies between 318.31 khz and 1007.0 Mhz

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