Chapter7: Integrated Circuit Timer And Phase Locked Loops (PLL)

Ex7.1:pg-339

In [20]:
#Ex 7.1
RA=6.8  #kohm
RB=3.3  #kohm
C=0.1  #micro F
VCC=5  #V
t_high=0.695*(RA+RB)*C  #ms
print round(t_high,1)," =(a) t_high(ms)  " 
t_low=0.695*RB*C  #ms
print round(t_low,2)," =(b) t_low(ms)  " 
f=1.44/(RA+2*RB)/(C)  #kHz
print round(f,2)," =(c) Frequency of oscillation(kHz)  " 

0.7  =(a) t_high(ms)  
0.23  =(b) t_low(ms)  
1.07  =(c) Frequency of oscillation(kHz)

Ex7.2:pg-339

In [21]:
#Ex 7.2
RA=10  #kohm
C=0.1  #micro F
t=1.1*RA*C  #ms
print t,"= Timing interval(ms)  " 

1.1 = Timing interval(ms)

Ex7.3:pg-352

In [7]:
#Ex 7.3 
fc=500  #kHz(Free running frequuency)
fi=600  #kHz(Input signal frequuency)
BW=10  #kHz
out1=fi+fc  #kHz(Phase detector output)
out2=fi-fc  #kHz(Phase detector output)
print out2,out1,"= Output of phase detector will be(kHz)  " 
print "Both components are not lying in the passband(i.e. 10 kHz). Hence loop will not acquire lock.  " 
 #fi+fc is calculated wrong in the book.

100 1100 = Output of phase detector will be(kHz)  
Both components are not lying in the passband(i.e. 10 kHz). Hence loop will not acquire lock.

Ex7.4:pg-352

In [28]:
#Ex 7.4
import math 
fo=10.0  #kHz
V=12.0  #V
fL=round(8*fo/(V-(-V)),2)  #kHz(both +ve & -ve value)
C=10  #micro F(Assumed)
fC=round(math.sqrt(fL*10**3/(2*math.pi*3.6*10**3*C*10**-6)),2)  #Fz(both +ve & -ve value)
print fC,fL,"= Frequency fL & fC in kHz  " 
LR=2*fL  #kHz(Lock Range)
print round(LR,1),"= Lock Range(kHz)  " 
CR=2*fC  #kHz(Capture rage)
print round(CR,1),"= Capture Range(Hz)  " 

121.33 3.33 = Frequency fL & fC in kHz  
6.7 = Lock Range(kHz)  
242.7 = Capture Range(Hz)

Ex7.5:pg-353

In [39]:
#Ex 7.5
import math
 
fo=100.0  #kHz(Free running frequency)
V=6.0  #V(both +ve & -ve value)
C=1  #micro F(Demodulation capacitor)
fL=round(8*fo/(V-(-V)),3) #Hz(both +ve & -ve value)
fC=math.sqrt(fL*1000/(2*math.pi*3.6*10**3*C*10**-6))  #kHzz(both +ve & -ve value)
LR=round(2*fL,2)  #kHz(Lock range)
print LR,"= Lock Range(kHz)" 
CR=round(2*fC/1000,2)  #kHz(Capture range)
print CR,"= Capture Range(kHz)  " 
RT=10  #kohm(Assumed)
CT=1.2/(4*RT*1000*fo*10**3)  #F
print "Design values are:" 
print "Resistance RT can be chooosen as 10 kohm.  "  
print CT," =Capacitance CT(F)  " 

133.33 = Lock Range(kHz)
3.43 = Capture Range(kHz)  
Design values are:
Resistance RT can be chooosen as 10 kohm.  
3e-10  =Capacitance CT(F)

Ex7.7:pg-355

In [41]:
 #Ex 7.7
import math
C=1  #nF
T=10  #micro seconds(Output pulse duration)
R=round(T*10**-6/(C*10**-9*math.log(3))/1000,1)  #kohm
print R," =(a) Value of R(kohm)  " 
VCC=15  #V
T=20  #micro seconds(Output pulse duration)
VTH=VCC*(1-exp(-T*10**-6/(R*1000*C*10**-9)))  #V
print round(VTH,1)," =(b) Value of VTH(V)  " 

9.1  =(a) Value of R(kohm)  
13.3  =(b) Value of VTH(V)

Ex7.8:pg-355

In [62]:
 #Ex 7.8
import math
C=680.0  #pF
f=50.0  #kHz(Square wave frequency)
D=75.0/100.0  #duty cycle
T=1/f*1000  #micro seconds
tHIGH=D*T  #micro seconds
print tHIGH," = Value of tHIGH  "
tLOW=T-tHIGH  #micro seconds
print tLOW," = Value of tLOW  " 
RB=(tLOW*10**-6)/(0.69*C*10**-12)  #ohm
RA=(tHIGH*10**-6)/(0.695*C*10**-12)-RB  #ohm
print round(RA/1000,1)," = Value of RA(kohm)  " 
print round(RB/1000,2)," = Value of RB(kohm)  " 
# Answer in the book is wrong for RA i.e. 21.2

15.0  = Value of tHIGH  
5.0  = Value of tLOW  
21.1  = Value of RA(kohm)  
10.66  = Value of RB(kohm)