# Chapter 9 : Solid State Microwave Devices¶

## Example 9.1 Page No : 387¶

In [1]:
import math

v_d = 10**7*10**-2                           #drift velocity(in m/s)
L = 2.*10**-6                                 #drift length(in m)

#calculations
f = v_d/(2*L)                                #in Hz
#---output---#
print 'Operating Frequency (in GHz) =',round(f/10**9,4)
Operating Frequency (in GHz) = 25.0

## Example 9.2 Page No : 392¶

In [2]:
import math

f=10*10**9                 #in Hz
L=75*10**-6                #Device length (in m)
V=25.                       #Voltage pulse amplified (in volts)

#calculations
E_th=V/L
#---output---#
print 'Threshold Electric field (in kV/cm) =',round(E_th,4)
Threshold Electric field (in kV/cm) = 333333.3333

## Example 9.3 Page No : 399¶

In [3]:
import math

f_s = 2*10**9                          #in Hz
f_p = 12*10**9                         #in Hz
R_i = 16
R_s = 1000
#calculations
A_p = 10*math.log((f_p-f_s)/f_s)
A_p_usb = 10*math.log((f_p+f_s)/f_s)
#---output---#
print 'Power gain (in dB) =',round(math.log(10),4)
print 'Power gain as USB converter (in dB) =',round(A_p_usb,4)
Power gain (in dB) = 2.3026
Power gain as USB converter (in dB) = 19.4591

## Example 9.4 Page No : 405¶

In [4]:
import math

E_s = 12.5
E_o = 8.85*10**-12
N = 3.2*10**22                         #per cubic meter
L = 8*10**-6                           #in m
q = 1.6*10**-19                        #in coulombs
#calculations
E = E_o*E_s
V_c = q*N*L**2/(2*E)
V_bd = 2*V_c
E_bd = V_bd/L

#---output---#
print 'Critical voltage(in kV) =',round(V_c/10**3,4)
print 'Breakdown Voltage (in kV) =',round(V_bd/10**3,4)
print 'Breakdown Electric field (in V/cm) =',round(E_bd,4)
Critical voltage(in kV) = 1.481
Breakdown Voltage (in kV) = 2.9621
Breakdown Electric field (in V/cm) = 370259887.006

## Example 9.5 Page No : 411¶

In [5]:
import math

N_a = 2.5*10**16                                #per cubic cm
J = 33                                          #in kA/cm**2
q = 1.6*10**-19

#calculations
V_z = J/(q*N_a)                                 #Avalanche zone velocity (in cm/s)
#---output---#
print 'Avalanche zone velocity (in cm/s) =',round(V_z,4)
Avalanche zone velocity (in cm/s) = 8250.0

## Example 9.6 Page No : 414¶

In [6]:
import math

R_neg = 25                    #in ohm

#calculations
#---output---#
print 'Power gain =',round(G,4)
Power gain = 9.0

## Example 9.7 Page No : 422¶

In [7]:
import math

L  = 5*10**-4                                                #in drift length

#calculations

#---output---#
print 'Minimum voltage needed (in Volts) =',round(V_min,4)
Minimum voltage needed (in Volts) = 1.65

## Example 9.8 Page No : 430¶

In [8]:
import math

v_d = 2.*10**7                           #in cm/s
L = 20.*10**-4                           #in cm

#calculations
f = v_d/L
critical_field = 3.3*10**3
V = L*critical_field

#---output---#
print 'Natural frequency (in GHz) =',round(f*10**-9,4)
print 'Critical voltage (in volts) =',round(V,4)
Natural frequency (in GHz) = 10.0
Critical voltage (in volts) = 6.6