Chapter - 18 : BJT BIASING AND STABILISATION¶

Ex 18.1 Pg 402¶

In [3]:
from __future__ import division
from numpy import arange
%matplotlib inline
from matplotlib.pyplot import plot,xlabel,ylabel,show
Vbb=10#
Rb=47*10**3#
Vcc=20#
Rc=10*10**3#
B=100#
Ic=Vcc/Rc##saturation current
print "Ic=%0.2f"%(Ic*10**3),'mA'
Vce=Vcc##cut-off voltage
print 'Vce=%0.2f'%Vce,"V"
i=arange(2,0,-0.1)
plot(i)#
xlabel("VCE")#
ylabel( "IC")#
show()

Ic=2.00 mA
Vce=20.00 V


Ex 18.2 Pg 403¶

In [4]:
from __future__ import division
from numpy import arange
%matplotlib inline
from matplotlib.pyplot import plot,xlabel,ylabel,show

Vbb=10#
Rb=50*10**3#
Vcc=20#
Rc=300#
beta=200#
Ic=Vcc/Rc##saturation current
print "IC=%0.2f"%(Ic*1e3),'mA'
Vce=Vcc##cut-off voltage
print 'Vce=%0.2f'%Vce,"V"
Ib=(Vbb-0.7)/Rb#
print "Ib=%0.2e"%Ib,"A"
Ic=beta*Ib#
print "Ic=%0.2e"%Ic,"A"
Vce=Vcc-Ic*Rc#
print 'Vce=%0.2f'%Vce,"V"
i=arange(21,0,-0.1)
plot(i)#
xlabel("VCE")#
ylabel( "IC")#
show()

IC=66.67 mA
Vce=20.00 V
Ib=1.86e-04 A
Ic=3.72e-02 A
Vce=8.84 V


Ex 18.3 Pg 404¶

In [5]:
from __future__ import division

Rb=180*10**3#
Vcc=25#
Rc=820#
beta=80#
Ib=Vcc/Rb##saturation current
print "Ib=%0.2f"%(Ib*1e3),'mA'
Ic=beta*Ib#
print "Ic=%0.2f"%(Ic*1e3),'mA'
Vce=Vcc-(Ic*Rc)##cut-off voltage
print 'Vce=%0.2f'%Vce,"V"

Ib=0.14 mA
Ic=11.11 mA
Vce=15.89 V


Ex 18.4 Pg 404¶

In [8]:
from __future__ import division

Vcc=12#
Rc=330#
Ib=0.3*10**-3#
beta=100#
#Ib=Vcc/Rb##saturation current
Rb=Vcc/Ib#
print "Rb=%0.2f"%(Rb*1e-3),'Kohm'
S=1+beta#
print "S=",S
Ic=beta*Ib#
print "Ic=%0.2e"%Ic,"A"
Vce=Vcc-(Ic*Rc)##cut-off voltage
print 'Vce=%0.2f'%Vce,"V"

Rb=40.00 Kohm
S= 101
Ic=3.00e-02 A
Vce=2.10 V


Ex 18.5 Pg 405¶

In [10]:
from __future__ import division

Rb=400*10**3#
Vcc=20#
Rc=2*10**3#
Re=1*10**3#
beta=100#
Ib=Vcc/(Rb+(beta*Re))##saturation current
print "Ib=%0.2f"%(Ib*10**3),'mA'
Ic=beta*Ib#
print "Ic=%0.2f"%(Ic*10**3),'mA'
Vce=Vcc-(Ic*(Rc+Re))##cut-off voltage
print 'Vce=%0.2f'%Vce,"V"

Ib=0.04 mA
Ic=4.00 mA
Vce=8.00 V


Ex 18.6 Pg 406¶

In [12]:
from __future__ import division
from numpy import arange
%matplotlib inline
from matplotlib.pyplot import plot,xlabel,ylabel,show

Vcc=12#
Rc=2.2*10**3#
Rb=240#
B=50#
Vbe=0.7#
RE=0#
Ic=(Vcc-Vbe)/(RE+(Rb/B))##collector current
print "Ic=%0.2f mA"%Ic
Vce=Vcc-(Ic*10**-3)*Rc##CE voltage
print 'VCe=%0.2f V'%Vce
Icsat=Vcc/Rc#
print 'Icsat=%0.2f mA'%(Icsat*10**3)
Vcec=Vcc##cutoff voltage
i=arange(5.45,0,-0.5)
plot(i)#
xlabel("VCE")#
ylabel( "IC")#
show()

Ic=2.35 mA
VCe=6.82 V
Icsat=5.45 mA


Ex 18.7 Pg 407¶

In [14]:
from __future__ import division
from numpy import arange
%matplotlib inline
from matplotlib.pyplot import plot,xlabel,ylabel,show

Vcc=30#
Rb=1.5*10**6#
Rc=5*10**3#
beta=100#
Ic=Vcc/Rc##saturation current
print 'Ic=%0.2f mA'%(Ic*10**3)
Vce=Vcc##cut-off voltage
print 'Vce=%0.2f V'%Vce
Ib=Vcc/Rb##base current
print 'Ib=%0.2f microA'%(Ib*10**6)
Ic=beta*Ib#
print 'Ic=%0.2f mA'%(Ic*10**3)
Vce=Vcc-Ic*Rc#
print 'Vce= %0.2f V'%Vce
i=arange(6,0,-0.2)
plot(i)#
xlabel("VCE")#
ylabel( "IC")#
show()

Ic=6.00 mA
Vce=30.00 V
Ib=20.00 microA
Ic=2.00 mA
Vce= 20.00 V


Ex 18.9 Pg 408¶

In [16]:
from __future__ import division

Rb=180*10**3#
Vcc=25#
Rc=820#
Re=200#
beta=80#
Vbe=0.7#
Ic=(Vcc-Vbe)/(Re+(Rb/beta))##collector current
print 'Ic=%0.2f mA'%(Ic*10**3)
Vce=Vcc-(Ic*Rc)##collector to emitter voltage
print 'Vce= %0.2f V'%Vce
S=(1+beta)/(1+beta*(Re/(Re+Rb)))#
print "S=%0.3f"%S##stability factor

Ic=9.92 mA
Vce= 16.87 V
S=74.394


Ex 18.10 Pg 409¶

In [17]:
from __future__ import division

Vbe=0.7#
Rb=100*10**3#
Vcc=10#
Rc=10*10**3#
beta=100#
Ic=(Vcc-Vbe)/(Rc+(Rb/beta))##collector current
print 'Ic=%0.2f mA'%(Ic*10**3)
Vce=Vcc-(Ic*Rc)##collector to emitter voltage
print 'Vce= %0.2f V'%Vce
Ic=Vcc/Rc#
print 'Ic=%0.2f mA'%(Ic*10**3)
Vce=Vcc#
print 'Vce= %0.2f V'%Vce

Ic=0.85 mA
Vce= 1.55 V
Ic=1.00 mA
Vce= 10.00 V


Ex 18.11 Pg 410¶

In [19]:
from __future__ import division

Rb=100*10**3#
Vcc=10#
Rc=2*10**3#
beta1=50#
Vbe=0.7#
Ib=(Vcc-Vbe)/(Rb+(beta1*Rc))#
print 'Ib=%0.2f mA'%(Ib*10**3)
Ic=beta1*Ib#
print 'Ic=%0.2f mA'%(Ic*10**3)
Ie=Ic#
print 'Ie=%0.2f mA'%(Ie*10**3)

Ib=0.05 mA
Ic=2.33 mA
Ie=2.33 mA


Ex 18.12 Pg 411¶

In [20]:
from __future__ import division

VCC=9#
RB=220*10**3#
RC=3.3*10**3#
VBE=0.3#
B=100#
#if vc=0
IB=(VCC-VBE)/(RB+(B*RC))#
print 'IB=%0.2f microA'%(IB*10**6)
IC=B*IB#
print 'IC=%0.2f microA'%(IC*10**6) #CORRECTION IN BOOK
#if VC=9
VC=9#
IC=B*IB#
print 'IC=%0.2f mA'%(IC*10**3)
#IC*RC=0,which means collector resistance is short circuited

IB=15.82 microA
IC=1581.82 microA
IC=1.58 mA


Ex 18.13 Pg 412¶

In [21]:
from __future__ import division

Vcc=12#
Rc=3.3*10**3#
Re=100#
Ie=2*10**-3#
Vbe=0.7#
alpha=0.98#
Ic=alpha*Ie#
print 'Ic=%0.2f mA'%(Ic*10**3)
Vb=Vbe+(Ie*Re)#
print 'Vb=%0.2f V'%Vb
Vc=Vcc-(Ic*Rc)##collector to emitter voltage
print 'Vc=%0.2f V'%Vc
R2=20*10**3#
IR2=Vc/R2#
print 'IR2=%0.2f mA'%(IR2*10**3)
Ib=Ie-Ic#
print 'Ib=%0.2f mA'%(Ib*10**3)
IR1=IR2+Ib#
print 'IR1=%0.2f mA'%(IR1*10**3)
R1=(Vc-Vb)/IR1#
print 'R1=%0.2f kohm'%(R1*10**-3)

Ic=1.96 mA
Vb=0.90 V
Vc=5.53 V
IR2=0.28 mA
Ib=0.04 mA
IR1=0.32 mA
R1=14.63 kohm


Ex 18.14 Pg 414¶

In [22]:
from __future__ import division

VCC=24#
RC=10*10**3#
RE=270#
VBE=0.7#
B=45#
VCE=5#
IC=(VCC-VCE)/RC#
print 'IC=%0.2f mA'%(IC*10**3)
RB=(2.6*10**3)*B#
print 'RB=%0.2f kohm'%(RB*10**-3)

IC=1.90 mA
RB=117.00 kohm


Ex 18.15 Pg 416¶

In [25]:
from __future__ import division

Rb=33*10**3#
Vcc=3#
Rc=1.8*10**3#
beta=90#
Vbe=0.7#
Ib=(Vcc-Vbe)/(Rb+(Rc*beta))##collector current
print 'Ib=%0.2f mA'%(Ib*10**3)
Ic=beta*Ib#
print 'Ic=%.2f mA'%(Ic*10**3)
Vce=Vcc-(Ic*Rc)##collector to emitter voltage
print 'Vce=%0.2f V'%Vce
S=(1+beta)/(1+beta*(Rc/(Rc+Rb)))#stability factor
print "S=%0.3f"%S

Ib=0.01 mA
Ic=1.06 mA
Vce=1.09 V
S=16.091


Ex 18.16 Pg 416¶

In [26]:
from __future__ import division

Vbe=0.7#
Vcc=10#
Rc=1*10**3#
beta=100#
R1=10*10**3#
R2=5*10**3#
Re=500#
Vb=Vcc*(R2/(R1+R2))#
print 'Vb=%0.2f V'%Vb
Ve=Vb-Vbe#
print 'Ve=%0.2f V'%Ve
Ie=Ve/Re#
print 'Ie=%02.f mA'%(Ie*10**3)
Ic=Ie#
print 'Ic=%02.f mA'%(Ic*10**3)
Vce=Vcc-(Rc+Re)#
print 'Ve=%0.2f V'%Ve

Vb=3.33 V
Ve=2.63 V
Ie=05 mA
Ic=05 mA
Ve=2.63 V


Ex 18.17 Pg 418¶

In [28]:
from __future__ import division

Vcc=9#
Rc=1*10**3#
Re=680#
beta=100#
R1=33*10**3#
R2=15*10**3#
Vb=Vcc*(R2/(R1+R2))#
print 'Vb=%0.2f V'%Vb
Vbe=0.7#
Ve=Vb-Vbe#
print 'Ve=%0.2f V'%Ve
Ie=Ve/Re#
print 'Ie=%0.2f mA'%(Ie*10**3)
Ic=Ie#
print 'Ic=%0.2f mA'%(Ic*10**3)
VRc=Ic*Rc#
print 'VRc=%0.2f V'%VRc
Vc=Vcc-VRc#
print 'Vc=%0.2f V'%Vc
Vce=Vc-Ve#
print 'Vce=%0.2f V'%Vce

Vb=2.81 V
Ve=2.11 V
Ie=3.11 mA
Ic=3.11 mA
VRc=3.11 V
Vc=5.89 V
Vce=3.78 V


Ex 18.18 Pg 419¶

In [29]:
from __future__ import division

VCC=5#
RE=0.3*10**3#
IC=1*10**-3#
VCE=2.5#
B=100#
VBE=0.7#
ICO=0#
R2=10*10**3#
IE=IC#
RC=((VCC-VCE)/IC)-RE#
print 'Rc=%0.2f ohm'%RC
VE=IE*RE#
VB=VE+VBE#
R1=VCC*R2-R2#
print 'R1=%0.2f kohm'%(R1*10**-3)

Rc=2200.00 ohm
R1=40.00 kohm


Ex 18.19 Pg 420¶

In [30]:
from __future__ import division

Vcc=20#
RC=1*10**3#
RE=5*10**3#
R1=10*10**3#
R2=10*10**3#
B=462#
VBE=0.7#
VB=Vcc*R2/(R1+R2)#
print 'VB=%0.2f V'%VB
VE=VB-VBE#
IE=VE/RE#
print 'IE=%0.2f mA'%(IE*10**3)
IC=IE#
VCE=Vcc-IC*RC#
print 'VCE=%0.2f V'%VCE

VB=10.00 V
IE=1.86 mA
VCE=18.14 V


Ex 18.20 Pg 422¶

In [31]:
from __future__ import division

VCC=8#
VRC=0.5#
RC=800#
a=0.96#
VCE=VCC-VRC##VRC=IC*RC
IC=VRC/RC#
print 'IC=%0.2f mA'%(IC*10**3)
IE=IC/a#
print 'IE=%0.2f mA'%(IE*10**3)
IB=IE-IC#
print 'IB=%0.2f microA'%(IB*10**6)

IC=0.62 mA
IE=0.65 mA
IB=26.04 microA


Ex 18.21 Pg 423¶

In [32]:
from __future__ import division

VCC=12#
RC=1*10**3#
RE=100#
R1=25*10**3#
R2=5*10**3#
B=50#
VBE=0.6#
VTH=VCC*R2/(R1+R2)#
RTH=R1*R2/(R1+R2)#
IE50=(VTH-VBE)/(RE+RTH/B)#
B=150#
IE150=(VTH-VBE)/(RE+RTH/B)#
ICdiff=(IE150-IE50)/IE50#
print "ICdiff=%0.3f %%"%(ICdiff*100)

ICdiff=43.478 %


Ex 18.24 Pg 424¶

In [33]:
from __future__ import division

B=50#
VBE=0.7#
VCC=22.5#
RC=5.6*10**3#
VCE=12#
IC=1.5*10**-3#
S=3#
RE=(VCC-IC*RC-VCE)/IC#
print 'RE=%0.2f kohm'%(RE*10**-3)
RTH=(4375)-RE#
print 'RTH=%0.2f kohm'%(RTH*10**-3)
R2=0.1*B*RE#
print 'R2=%0.2f kohm'%(R2*10**-3)
R1=(-RTH*R2)/(RTH-R2)#
print 'R1=%0.2f kohm'%(R1*10**-3)

RE=1.40 kohm
RTH=2.98 kohm
R2=7.00 kohm
R1=5.17 kohm


Ex 18.25 Pg 425¶

In [1]:
from __future__ import division

VCC=10#
VEE=10#
RC=1*10**3#
RE=5*10**3#
RB=50*10**3#
VBE=0.7#
VE=-VBE#
IE=(VEE-VBE)/RE#
print 'Ie=%0.2f mA'%(IE*10**3)
IC=IE#
print 'IC=%0.2f mA'%(IC*10**3)
VC=VCC-IC*RC#
VCE=VC-VE#
print 'VCE=%0.2f V'%VCE

Ie=1.86 mA
IC=1.86 mA
VCE=8.84 V


Ex 18.26 Pg 426¶

In [2]:
from __future__ import division

VCC=20#
VEE=20#
RC=5*10**3#
RE=10*10**3#
RB=10*10**3#
B1=50#
B2=100#
VBE1=0.7#
VBE2=0.6#
IE1=(VEE-VBE1)/(RE+RB/B1)#
print 'IE1=%0.2f mA'%(IE1*10**3)
IC1=IE1#
VC1=VCC-IC1*RC#
print 'VC1=%0.2f V'%VC1
VE=-VBE1#
VCE1=VC1-VE#
print 'VCE1=%0.2f V'%VCE1
IE2=(VEE-VBE2)/(RE+RB/B2)#
print 'IE2=%0.2f mA'%(IE2*10**3)
IC2=IE2#
VC2=VCC-IC2*RC#
print 'VC2=%0.2f V'%VC2
VE=-VBE2#
VCE2=VC-VE#
print 'VCE2=%0.2f V'%VCE2
delIc=(IC2-IC1)/IC1#
print "delIc=%0.2f %%"%(delIc*100)
delVCE=(VCE1-VCE2)/VCE2#
print "delVCE=%0.2f %%"%(delVCE*100)

IE1=1.89 mA
VC1=10.54 V
VCE1=11.24 V
IE2=1.92 mA
VC2=10.40 V
VCE2=8.74 V
delIc=1.51 %
delVCE=28.60 %


Ex 18.27 Pg 427¶

In [3]:
from __future__ import division

VCC=12#
RC=2*10**3#
RE=1*10**3#
R1=100*10**3#
R2=20*10**3#
B=100#
VBE=-0.2#
VB=-VCC*R2/(R1+R2)#
print 'VB=%0.2f V'%VB
VE=VB-VBE#
print 'VE=%0.2f V'%VE
IE=-VE/RE#
IC=IE#
print "IC=%0.2f mA"%(IC*10**3)
VC=-(VCC-IC*RC)#
print 'VC=%0.2f V'%VC
VCE=VC-(VE)#
print 'VCE=%0.2f V'%VCE

VB=-2.00 V
VE=-1.80 V
IC=1.80 mA
VC=-8.40 V
VCE=-6.60 V


Ex 18.28 Pg 428¶

In [4]:
from __future__ import division

VCC=4.5#
RC=1.5*10**3#
RE=0.27*10**3#
R2=2.7*10**3#
R1=27*10**3#
B=44#
VBE=-0.3#
VB=-VCC*R2/(R1+R2)#
print 'VB=%0.2f V'%VB
VE=VB-VBE#
print 'VE=%0.2f V'%VE
IE=-VE/RE#
IC=IE#
print 'IC=%0.2f mA'%(IC*10**3)
VRC=IC*RC#
print 'VRC=%0.2f V'%VRC
VC=-(VCC-VRC)
print 'VC=%0.2f V'%VC
VCE=VC-(VE)#
print 'VCE=%0.2f V'%VCE

VB=-0.41 V
VE=-0.11 V
IC=0.40 mA
VRC=0.61 V
VC=-3.89 V
VCE=-3.78 V