Chapter 6 - BJT at High Frequency

PageNumber 337 example 1

In [1]:
colcur=10*10**-3##ampere
vce=10##volt
hie=500##ohm
hoe=4*10**-5
hfe=100
hre=1*10**-4
fqu=50*10**6##hertz
q=3*10**12##farad
voltag=26*10**-3##volt
g=colcur/voltag
gbe=g/hfe
gbc=gbe*hre
rbb=hie-260
oucond=hoe-(1+hfe)*gbc
cbe=g/(2*3.14*fqu)
rbc=1/gbc
rce=1/oucond
print "transconductance g   =   %0.2f"%((g)),"ampere/volt"
print "input conductance gbe   =   %0.2e"%((gbe)),"ampere/volt"
print "feedback conductance gbc   =   %0.2e"%((gbc)),"ampere/volt"
print "base spread resistance rbb   =   %0.2f"%((rbb)),"ohm"
print "output conductance   =   %0.2e"%((oucond)),"ampere/volt"
print "transition capacitance cbe   =   %0.2e"%((cbe)),"farad"
print "rbc    =   %0.2e"%((rbc)),"ohm"##correction as 2.6mega ohm
print "rce   =   %0.2e"%((rce)),"ohm"

transconductance g   =   0.38 ampere/volt
input conductance gbe   =   3.85e-03 ampere/volt
feedback conductance gbc   =   3.85e-07 ampere/volt
base spread resistance rbb   =   240.00 ohm
output conductance   =   1.15e-06 ampere/volt
transition capacitance cbe   =   1.22e-09 farad
rbc    =   2.60e+06 ohm
rce   =   8.67e+05 ohm

PageNumber 337 example 2

In [2]:
colcur=5*10**-3##ampere
vce=10##volt
hfe=100
hie=600##ohm
cugain=10
fqu=10*10**6##hertz

tracat=3*10**-12##farad
voltag=26*10**-3##volt
fbeta1=((((hfe**2)/(cugain**2))-1)/fqu**2)**(1/2)
fbeta1=1/fbeta1
fq1=hfe*fbeta1
cbe=colcur/(2*3.14*fq1*voltag)
rbe=hfe/(colcur/voltag)
rbb=hie-rbe
print "fbeta   =   %0.2f"%((fbeta1)),"hertz"
print "f   =   %0.2f"%((fq1)),"hertz"
print "cbe   =   %0.2e"%((cbe)),"farad"
print "rbe   =   %0.2f"%((rbe)),"ohm"
print "rbb   =   %0.2f"%((rbb)),"ohm"

fbeta   =   1.00 hertz
f   =   100.00 hertz
cbe   =   3.06e-04 farad
rbe   =   520.00 ohm
rbb   =   80.00 ohm

PageNumber 338 example 3

In [3]:
w=1*10**-4##centimetre
em1cur=2*10**-3##ampere
q=47
voltag=26*10**-3##volt
cde=(em1cur*w**2)/(voltag*2*q)
fq1=(em1cur)/(2*3.14*cde*voltag)
print "cde   =   %0.2e"%((cde)),"farad"
print "frequency   =   %0.2e"%((fq1)),"hertz"

cde   =   8.18e-12 farad
frequency   =   1.50e+09 hertz

PageNumber 339 example 6

In [4]:
w=5*10**-4##centimetre
em1cur=2*10**-3##ampere
q=47
voltag=26*10**-3##volt
re=voltag/em1cur
fq1=2*q/(w**2*2*3.14)
cde=(em1cur*w**2)/(voltag*2*q)
w=(w**2)/(2*q)
print "re   =   %0.2f"%((re)),"ohm"
print "falpha   =   %0.2e"%((fq1)),"hertz"
print "cde   =   %0.2e"%((cde)),"farad"
print "w   =   %0.2e"%((w)),"second"

re   =   13.00 ohm
falpha   =   5.99e+07 hertz
cde   =   2.05e-10 farad
w   =   2.66e-09 second

PageNumber example 8

In [5]:
w=10**-6##centimetre
em1cur=4*10**-3##ampere
voltag=26*10**-3##volt
q=47
cde=(em1cur*w**2)/(voltag*2*q)
fq1=(em1cur)/(2*3.14*cde*voltag)
print "f   =   %0.2e"%((fq1)),"hertz"
print "cde   =   %0.2e"%((cde)),"farad"##correction required in the book.

f   =   1.50e+13 hertz
cde   =   1.64e-15 farad