# Chapter 8 - FET Amplifier¶

## PageNumber 399 example 1¶

In [1]:
from math import sqrt
freque=5*10**3##hertz
#(1)
g=2*10**-3##ampere per volt
rd=10*10**3##ohm
r1=30*10**3##ohm
r12=r1*r1/(r1+r1)
volgai=-(g*r12*rd)/(r12+rd)
print "voltage gain   =   %0.2f"%((volgai))
#correction : r12 should be taken as 15*10**3ohm in book
#(2) capacitance included
frequ1=1/((2*3.14*(((rd*r1)/(rd+r1))+r1))*c)
volgai=(volgai/(sqrt((1+(frequ1/freque)**2))))

print "voltage gain   =   %0.2f"%((volgai))

voltage gain   =   -12.00
voltage gain   =   -11.99


## PageNumber 400 example 2¶

In [2]:
rd=80*10**3##ohm
r1=8*10**3##ohm
rd12=5*10**3##ohm
rd1=rd*r1/(rd+r1)
u=30
volgai=-(u*rd1)/(rd1+rd12)

print "voltage gain   %0.2f"%((volgai))

voltage gain   -18.00


## PageNumber 401 example 3¶

In [3]:
r1=60*10**3##ohm
volgai=-17.7
rg=80*10**3##ohm
volgai=((volgai*rg)/(1-volgai))/((rg/(1-volgai))+r1)
print "voltage gain   =   %0.2f"%((volgai))

voltage gain   =   -1.18


## PageNumber 405 example 6¶

In [4]:
vds=14##volt
idq=3*10**-3##ampere
vdd=20##volt
g=2*10**-2
rd=50*10**3##ohm
vgs=-1.5##volt
w=(vdd-vds)/idq
r1=-vgs/idq
r2=w-r1
inpres=1/(1-(0.8*((r1)/(r1+r2))))
volgai=(r1+r2)/(r1+r2+(1/(g)))
print "r1   =   %0.2f"%((r1)),"ohm"
print "effective input resistance   =   %0.2f"%((inpres)),"r3ohm"
print "r2   =   %0.2f"%((r2)),"ohm"

print "voltage gain   =   %0.2f"%((volgai)),"av"

r1   =   500.00 ohm
effective input resistance   =   1.25 r3ohm
r2   =   1500.00 ohm
voltage gain   =   0.98 av


## PageNumber 405 example 7¶

In [5]:
rg=40*10**3##ohm
voltag=(1-6*50)*3.3*10**3/(5.3*10**3)

print "output voltage   =   %0.2f"%((voltag)),"volt"#
#correction required in the book

output voltage   =   -186.17 volt


## PageNumber 406 example 9¶

In [6]:
u=50
rd=10*10**3##ohm
freque=3##decibel
g=u/rd
volgai=-u*rd/(rd+rd)
req=rd*rd/(rd+rd)
frequ1=1/(2*3.14*cgd*req)
print "voltage gain   =   %0.2f"%((volgai))
#correction required in book
print "frequency   =   %0.2e"%((frequ1)),"hertz"
capac1=cgd*(1+g)

voltage gain   =   -25.00