Chapter8:AVALANCHE TRANSIT-TIME DEVICES

Eg8.2.1:pg-331

In [1]:
#(a)Calculate the maximum CW power
n=0.15             #efficiency
Vomax=100          #maximum operating voltage in volt
Iomax=200*(10**-3) #maximum operating current in ampere
Pdc=Vomax*Iomax 
P=n*Pdc 
print"The maximum CW power(in Watts)is =",int(P),"W"

#(b) Calculate the resonant frequency
L=6*(10**-6)      #drift-region Length in meter
vd=2*(10**5)      #carrier drift velocity in m/s
f=vd/(2*L) 
f=f/(10**9)  #in GHz
print"The resonant frequency(in GHz)is =",round(f,2),"GHz"

The maximum CW power(in Watts)is = 3 W
The resonant frequency(in GHz)is = 16.67 GHz

Eg8.3.1:pg-334

In [2]:
#calculate the avalanche-zone velocity
J=20*(10**3)     #current density in A/cm**2
q=1.6*(10**-19)  #charge of electron in C
NA=2*(10**15)    #Doping Concentration in /cm**3
vs=J/(q*NA) 
print"Avalanche-zone velocity(in cm/s)is =","{:.2e}".format(vs),"cm/s"

print('This means that the avalanch-zone velocity is much larger than the scattering-limited velocity') 

Avalanche-zone velocity(in cm/s)is = 6.25e+07 cm/s
This means that the avalanch-zone velocity is much larger than the scattering-limited velocity

Eg8.4.1:pg-338

In [3]:
#(a) Calculate the break down voltage
q=1.6*(10**-19)   #charge of electron
N=2.8*(10**21)    #Donor Concentration /m**3
L=6*(10**-6)      #silicon length in meter
er=11.8           #Relative dielectric constant of silicon
es=8.854*(10**-12)*er #permittivity of silicon in F/m
Vbd=(q*N*(L**2))/es 
print"The break down voltage(in Volts) is =",round(Vbd,2),"V" 

#(b)Calculate the break down electric field
Ebd=Vbd/L 
print"the break down electric field is =","{:.3e}".format(Ebd),"V/m =","{:.3e}".format(Ebd/100),"V/cm" 

The break down voltage(in Volts) is = 154.37 V
the break down electric field is = 2.573e+07 V/m = 2.573e+05 V/cm

Eg8.5.1:pg-346

In [5]:
import math
#(a)Calculate the power gain in decibels
R=25             #R=f0/fs ,ratio of output frequency over signal frequency
yQ=10            #figure of merit
x=((yQ)**2)/R 
PG=(R*x)/((1+sqrt(1+x))**2) 
PG=10*math.log10(PG)  #calculating in dB
print"The power gain (in dB)is =",round(PG,3),"dB" 

#(b)Calculate the noise figure in decibels

Td=350          #Diode temperature in degree Kelvin
To=300          #ambient Temperature in degree Kelvin
F=1+(((2*Td)/To)*((1.0/yQ)+(1.0/yQ**2)))
F=10*log10(F)   #calculating in dB
print"The noise figure (in dB)is =",int(round(F)),"dB"

#(c)Calculate the band width
y=0.4            #factor of merit figure
BW=2*y*sqrt(R)   #R=fo/fs
print"The band width is =",int(BW)

The power gain (in dB)is = 9.8 dB
The noise figure (in dB)is = 1 dB
The band width is = 4