CHAPTER 8 TRANSISTOR BIASING

Example 8-1, Page 263

In [1]:
VCC=10                  #collector voltage(V)
RC=3.6                  #Collector resistance (KOhm)
RE=1                    #Emitter resistance (KOhm)
R1=10                   #Base resistance1 (KOhm)
R2=2.2                  #Base resistance2 (KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)

VBB=(R2/(R1+R2))*VCC    #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/RE                #Emitter current(mA)
IC=IE                   #Collector current(mA)
VC=VCC-(IC*RC)          #collector to ground voltage(V)
VCE=VC-VE               #Collector-emitter voltage(V)

print 'Collector current IC = ',round(IC,2),'mA'
print 'Collector-emitter voltage VCE = ',round(VCE,2),'V'

Collector current IC =  1.1 mA
Collector-emitter voltage VCE =  4.92 V

Example 8-3, Page 267

In [2]:
VCC=10                  #collector voltage(V)
RC=3.6                  #Collector resistance (KOhm)
RE=1                    #Emitter resistance (KOhm)
R1=10                   #Base resistance1 (KOhm)
R2=2.2                  #Base resistance2 (KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)
Bdc=200                 #current gain

R=(R1*R2)/(R1+R2)       #Thevenin resistance(KOhm)
Ri=Bdc*RE               #Base input resistance(KOhm)
R100=0.01*Ri            #100th of Ri(KOhm)
VBB=(R2/(R1+R2))*VCC    #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/(RE+(R/Ri))       #Emitter current(mA)

print 'As per stiff voltage divider rule, R1||R2 < 0.01 Bdc*RE, So, Voltage divider is stiff.'
print 'Emitter current IE = ',round(IE,2),'mA'

As per stiff voltage divider rule, R1||R2 < 0.01 Bdc*RE, So, Voltage divider is stiff.
Emitter current IE =  1.09 mA

Example 8-4, Page 269

In [3]:
VCC=10                  #collector voltage(V)
IC=10                   #Collector current(mA)
VBE=0.7                 #Base-emitter voltage drop(V)
Bdc=100                 #current gain

IE=IC                   #Emitter current(mA)
VE=0.1*VCC              #Emitter voltage(V)
RE=(VE/IE)*1000         #Emitter resistance (Ohm)
RC=4*RE                 #Collector resistance(Ohm)
R2=0.01*Bdc*RE          #Base input resistance2(Ohm)
V2=VE+VBE               #voltage across R1(V)
V1=VCC-V2               #voltage across R2(V)
R1=(V1/V2)*R2           #Base input resistance1(Ohm)

print 'Emitter resistance RE = ',RE,'Ohm'
print 'Collector resistance RC = ',RC,'Ohm'
print 'Base resistance R1 = ',round(R1,2),'Ohm'
print 'Base resistance R2 = ',R2,'Ohm'

Emitter resistance RE =  100.0 Ohm
Collector resistance RC =  400.0 Ohm
Base resistance R1 =  488.24 Ohm
Base resistance R2 =  100.0 Ohm

Example 8-5, Page 271

In [4]:
VCC=10                  #collector voltage(V)
RC=3.6                  #Collector resistance (KOhm)
RE=1.8                  #Emitter resistance (KOhm)
RB=2.7                  #Base resistance (KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)
VEE=2                   #emitter voltage(V)

VBB=0                   #Base voltage(V)
VE=VEE-VBE              #Emitter to ground voltage(V)
IE=VE/RE                #Emitter current(mA)
IC=IE                   #Collector current(mA)
VC=VCC-(IC*RC)          #collector to ground voltage(V)

print 'Emitter current IE = ',round(IE,2),'mA'
print 'Collector voltage VC = ',VC,'V'

Emitter current IE =  0.72 mA
Collector voltage VC =  7.4 V

Example 8-6, Page 271

In [11]:
VCC=15                  #collector voltage(V)
RC=10                   #Collector resistance (KOhm)
RE=20                   #Emitter resistance (KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)
VEE=15                   #emitter voltage(V)

VBB=0                   #Base voltage(V)
VE=VEE-VBE              #Emitter to ground voltage(V)
IE=VE/RE                #Emitter current(mA)
IC=IE                   #Collector current(mA)
VC=VCC-(IC*RC)          #collector to ground voltage(V)

print 'Emitter current IE = ',IE,'mA'
print 'Collector voltage VC = ',VC,'V'

Emitter current IE =  0.715 mA
Collector voltage VC =  7.85 V

Example 8-7, Page 278

In [5]:
VCC=-10                 #collector supply voltage(V)
VEE=-VCC                #Emitter supply voltage(V)
RC=3.6                  #Collector resistance (KOhm)
RE=1                    #Emitter resistance (KOhm)
R1=10                   #Base resistance1 (KOhm)
R2=2.2                  #Base resistance2 (KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)

V2=(R2/(R1+R2))*VEE     #Base voltage(V)
IE=(V2-VBE)/RE          #Emitter current(mA)
VC=IE*RC                #collector to ground voltage(V)
VB=VEE-V2               #Base to ground voltage(V)
VE=VEE-(V2-VBE)         #Emitter to ground voltage(V)

print 'Emitter current IE = ',round(IE,2),'mA'
print 'Collector to ground voltage VC = ',round(VC,2),'V'
print 'Base to ground voltage VB = ',round(VB,2),'V'
print 'Emitter to ground voltage VE = ',round(VE,2),'V'

Emitter current IE =  1.1 mA
Collector to ground voltage VC =  3.97 V
Base to ground voltage VB =  8.2 V
Emitter to ground voltage VE =  8.9 V
In [ ]: