CHAPTER 11 CC AND CB AMPLIFIERS

Example 11-1, Page 348

In [12]:
VCC=10                #collector voltage(V)
RE=4.3                #Emitter resistance(KOhm)
R1=10                 #Base resistance1 (KOhm)
R2=10                 #Base resistance2 (KOhm)
VBE=0.7               #Base-emitter voltage drop(V)
RL=10                 #Load Resistance(KOhm)
VG=1                  #Input voltage(mV)
RG=0.6                #internal resistance of source(KOhm)
B=200                   #current gain 

VBB=VCC/2               #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/RE                #Emitter current(mA)
re1=(25/IE)             #AC resistance(Ohm)
re=RE*RL/(RE+RL)      #external ac resistance(KOhm)
Zin_base=(re+(re1/1000))*B                               #input impedance of base(KOhm)
Zin_stage=((R1**-1)+(Zin_base**-1)+(R2**-1))**-1  #input impedance of stage(KOhm)

print 'input impedance of stage Zin(base) = ',round(Zin_base,2),'KOhm'
print 'input impedance of stage Zin(stage) = ',round(Zin_stage,2),'KOhm'

input impedance of stage Zin(base) =  606.4 KOhm
input impedance of stage Zin(stage) =  4.96 KOhm

Example 11-2, Page 349

In [11]:
re=3.03               #Emitter resistance(KOhm)
VG=1                  #Input voltage(mV)
RG=0.6                #internal resistance of source(KOhm)
B=200                 #current gain 
Zin=5                 #input impedance(KOhm)

Vin=(Zin/(Zin+RG))*VG #input voltage(V)

print 'Input voltage Vin = ',round(Vin,2),'V'

Input voltage Vin =  0.89 V

Example 11-3, Page 350

In [10]:
VCC=15                #collector voltage(V)
RE=2.2                #Emitter resistance(KOhm)
R1=4.7                #Base resistance1 (KOhm)
R2=4.7                #Base resistance2 (KOhm)
VBE=0.7               #Base-emitter voltage drop(V)
RL=6.8                #Load Resistance(KOhm)
VG=1                  #Input voltage(mV)
RG=0.6                #internal resistance of source(KOhm)
B=150                   #current gain 

VBB=VCC/2.0             #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/RE                #Emitter current(mA)
re1=(25/IE)             #AC resistance(Ohm)
re=RE*RL/(RE+RL)        #external ac resistance(KOhm)
Zin_base=(re+(re1/1000))*B             #input impedance of base(KOhm)
Zin_stage=((R1**-1)+(R2**-1))**-1      #input impedance of stage(KOhm)
Av=re/(re+(re1/1000))                  #Voltage gain of stage
Vin=(Zin_stage/(Zin_stage+RG))*VG      #input voltage(V)
Vout=Av*Vin                            #output voltage(V)


print 'input impedance of stage Zin(base) = ',round(Zin_base,2),'KOhm'
print 'input impedance of stage Zin(stage) = ',Zin_stage,'KOhm'
print 'voltage gain of emitter follower Av = ',round(Av,3)
print 'Output volatge Vout = ',round(Vout,2),'V'

input impedance of stage Zin(base) =  250.55 KOhm
input impedance of stage Zin(stage) =  2.35 KOhm
voltage gain of emitter follower Av =  0.995
Output volatge Vout =  0.79 V

Example 11-4, Page 353

In [31]:
RG=600                #internal resistance of source(KOhm)
B=300                 #current gain 

Zout=RG/B             #Output impedance(KOhm)

print 'Output impedance Zout = ',Zout,'Ohm'

Output impedance Zout =  2 Ohm

Example 11-5, Page 353

In [6]:
VCC=30                #collector voltage(V)
RE=0.1                #Emitter resistance(KOhm)
R1=10                 #Base resistance1 (KOhm)
R2=10                 #Base resistance2 (KOhm)
RL=0.1                #Load Resistance(KOhm)
VG=1                  #Input voltage(mV)
RG=0.6                #internal resistance of source(KOhm)
B=300                 #current gain 

VBQ=VCC/2.0             #Base voltage(V)
VEQ=VBQ                 #Emitter voltage(V), ignore VBE
IEQ=VEQ/RE              #Emitter current(mA)
re=(25/IEQ)             #AC resistance(Ohm)
Zb=((RG**-1)+(R1**-1)+(R2**-1))**-1      #impedance looking back from base(KOhm)
Z=Zb*1000/B                              #impedance after current gain (Ohm) 
Ze=Z+re                                  #impedance looking back into emitter(Ohm)
Zout=(((RE*1000)**-1)+(Ze**-1))**-1             #Output impedance(Ohm)

print 'Output impedance is Zout = ',round(Zout,2),'Ohm'

Output impedance is Zout =  1.91 Ohm

Example 11-6, Page 355

In [5]:
VCC=10                  #collector voltage(V)
RE=0.68                 #Emitter resistance(KOhm)
RC=3.6                  #Collector resistance (KOhm)
re=0.18                 #Emitter resistance (KOhm)
R1=10                   #Base resistance1 (KOhm)
R2=2.2                  #Base resistance2 (KOhm)
RG=0.6                  #internal resistance of source(KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)
RL=0.27                 #Load resistance(KOhm)
B=100                   #current gain 

VBB=(R1*R2/(R1+R2))     #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/RE                #Emitter current(mA)
re=(25/IE)              #AC resistance(Ohm)
Zin=B*RL                #input impedance (KOhm)
rc=((RC**-1)+(Zin**-1))**-1 #ac collector resistance(KOhm)
Av=rc/(re/1000)             #voltage gain of stage

print 'voltage gain of CE stage Av = ',round(Av,2)

voltage gain of CE stage Av =  206.15

Example 11-7, Page 355

In [4]:
VCC=10                  #collector voltage(V)
RE=0.68                 #Emitter resistance(KOhm)
RC=3.6                  #Collector resistance (KOhm)
re=0.18                 #Emitter resistance (KOhm)
R1=10.0                   #Base resistance1 (KOhm)
R2=2.2                  #Base resistance2 (KOhm)
RG=0.6                  #internal resistance of source(KOhm)
VBE=0.7                 #Base-emitter voltage drop(V)
RL=0.27                 #Load resistance(KOhm)
B=100                   #current gain 

VBB=10*(R2/(R1+R2))     #Base voltage(V)
VE=VBB-VBE              #Emitter voltage(V)
IE=VE/RE                #Emitter current(mA)
re=(25/IE)              #AC resistance(Ohm)
rc=((RC**-1)+(RL**-1))**-1 #ac collector resistance(KOhm)
Av=rc/(re/1000)             #voltage gain of stage

print 'voltage gain of CE stage Av = ',round(Av,2)

voltage gain of CE stage Av =  16.3

Example 11-8, Page 358

In [3]:
VCC=15                   #collector voltage(V)
RE=0.06                  #Emitter resistance(KOhm)
R1=10.0                    #Base resistance1 (KOhm)
R2=20.0                    #Base resistance2 (KOhm)
RG=0.6                   #internal resistance of source(KOhm)
VBE=0.7                  #Base-emitter voltage drop(V)
RL=0.03                  #Load resistance(KOhm)
B1=100                   #current gain of Q1
B2=100                   #current gain of Q2

B=B1*B2                 #Overall current gain
VBB=15*(R2/(R1+R2))  #Base voltage(V)
VE=VBB-(2*VBE)              #Emitter voltage(V)
IE2=VE/RE                #Emitter current(mA)
IB2=IE2/B2               #Base current of Q2(mA)
IE1=IB2                  #emiter current of Q1(mA)
IB1=IE1*1000/B1               #base current of Q1(uA)
re=((RE**-1)+(RL**-1))**-1 #ac emitter resistance(KOhm)
Zin_base=B*re              #input impedance of Q1(KOhm)

print 'Overall current gain B = ',B
print 'base current of Q1 IB1 = ',round(IB1,2),'uA'
print 'input impedance at base of Q1 Zin(base) = ',Zin_base,'KOhm'

Overall current gain B =  10000
base current of Q1 IB1 =  14.33 uA
input impedance at base of Q1 Zin(base) =  200.0 KOhm

Example 11-9, Page 361

In [2]:
Vin=20                   #input voltage (V)
RL=15                    #Load resistance(Ohm)
Vz=10                    #voltage across zener(V)
B=100                    #current gain
Rs=680.0                 #series resistor(Ohm)

Vout=Vz-0.7              #Output voltage approx.(V)
Iout=Vout/RL             #Load current(A)
IB=Iout*1000/B           #base current(mA)
Is=(Vin-Vz)*1000/Rs      #current through series resistor(mA)
Iz=Is-IB                 #zener current(mA)

print 'output voltage Vout = ',Vout,'V'
print 'Zener current Iz = ',round(Iz,2),'mA'

output voltage Vout =  9.3 V
Zener current Iz =  8.51 mA

Example 11-10, Page 362

In [74]:
Vin=30                   #input voltage (V)
RL=100                   #Load resistance(Ohm)
Vz=6.2                   #voltage across zener(V)
B=100                    #current gain
Rs=680.0                 #series resistor(Ohm)
R1=1                     #Resistor (KOhm)
R2=2                     #Resistor (KOhm)

Vout=(Vz+0.7)*(R1+R2)/R1    #Output voltage approx.(V)
I1=(Vz+0.7)/R1              #Load current(A)
Vout=I1*(R1+R2)             #Output voltage(V)

print 'output voltage Vout = ',Vout,'V'

output voltage Vout =  20.7 V

Example 11-11, Page 365

In [1]:
VG=2                    #AC input voltage (mV)
Vs=10                    #supply volatge(V)
RL=10                    #Load resistance(KOhm)
RG=50.0                  #source resistor(Ohm)
R1=10                    #Resistor (KOhm)
R2=2.2                   #Resistor (KOhm)
RC=3.6                   #collector resistor (KOhm)
RE=2.2                   #emitter resistance(KOhm)

VB=Vs*R2/(R1+R2)              #Base voltage(V)
IE=(VB-0.7)*1000/RE           #emitter current(uA)
re=(25/IE)*1000               #ac resistance(Ohm)
Zin=1000*((RE**-1)+((re/1000)**-1))**-1   #input impedance(KOhm)
Zout=RC                       #Output impedance(KOhm)
rc=((RC**-1)+(RL**-1))**-1    #collector resistance(KOhm)
Av=rc*1000/re                      #voltage gain
Vin=(Zin/(Zin+RG))*VG              #input voltage(V)
Vout=Av*Vin                        #output voltage(mV)

print 'output voltage Vout = ',round(Vout,2),'mVpp'

output voltage Vout =  52.43 mVpp
In [ ]: