# Chapter 13: Detectors and Mixers¶

## Example 13.1, Page 546¶

In [1]:
import math

#Variable declaration
P=10000.   #average power (W)
V=1000.    #amplitude (V)

#Calculations&Results
W1=4*math.pi*10**6
Wc=2*math.pi*10**8
alpha = P/V**2
print "alpha=%.2f"%alpha
#(b)=
A=1000+2*225+2*150+2*75
peak_power=alpha*A**2
print "A=%.0f V\npeak_power=%.0f W"%(A,peak_power)

alpha=0.01
A=1900 V
peak_power=36100 W


## Example 13.2, Page 551¶

In [2]:
#Variable declaration
n=1
q=1.602*10**-19  #C
k=1.38*10**-23
T=290            #K
Is=10**-8        #A

#Calculations&Results
a=q/(n*k*T)
Ib=0            #A
Rj=1/(a*(Ib+Is))
print "(a)Rj=%d kohm"%(Rj*10**-3)
Ib=100*10**-6
Rj=1/(a*(Ib+Is))
print "(b)Rj=%.1f ohm"%Rj

(a)Rj=2498 kohm
(b)Rj=249.8 ohm


## Example 13.3, Page 557¶

In [3]:
#Variable declaration
fc = 5*10**6   #hz
Vm = 1         #V
fm = 1*10**3   #Hz

#Calculations&Results
#(a)
#Since the i/p frequency is multiplied by 12
fd = 10*12  #Hz
print "Frequency deviation at output = +/-%d KHz"%fd

#(b)
fosc = 55*10**6  #i/p signal from oscillator (Hz)
fs = fosc+fc+fd*10**3
print "\nSum frequency at output = %.2f MHz"%(fs*10**-6)

#(c)
a=1
delf=10*1000
fm=1000
B=a*delf/fm
print "\nFrequency deviation = %d"%B

#(d)
a=2
delf=10*1000
fm=500
B=a*delf/fm
print "\nFrequency deviation = %d "%B

Frequency deviation at output = +/-120 KHz

Sum frequency at output = 60.12 MHz

Frequency deviation = 10

Frequency deviation = 40


## Example 13.5, Page 573¶

In [5]:
#Variable declaration
IDss=50*10**-3  #mA
gm=200*10**-3   #mS
VL=.25         #V
RL=50          #ohms

#Calculations&Results
Vp=2*VL         #V
#gm=-2*IDss/Vp
Vp=2*IDss/gm    #V
print "Vp=%.2f V"%Vp
gc=IDss/(2*Vp)
print "gc=%.e S"%gc
Av=gc*RL
print "Av=%.1f"%Av

Vp=0.50 V
gc=5e-02 S
Av=2.5