Chapter 2: Circuit configuration for linear IC's

Example No. 2.1, Page no:40

In [1]:
#Variable Declaration:
Vcc=5.0              #voltage Vcc in volt
Vbeon=0.6            #Voltage  Vbeon in volt
Beta=150.0           #gain
Io=100.0*10**-6      #output current in amperes

#Calculations:
Iref=Io*(1+ 2/Beta)  #calculating reference current
Iref=Iref*10**6      #calculating reference current

R=(Vcc-Vbeon)/Iref   #Calculating value of resistance
R=R*1000.0           #Calculating value of resistance

#Results:
print("Iref= %.2f uA"% Iref)
print("\nResistance= %.2f kohm"% R)

Iref= 101.33 uA

Resistance= 43.42 kohm

Example No. 2.2, Page No:40

In [2]:
#Variable Declarations:
Vbe=0.7             #voltage Vbe in volt
Vcc=12.0            #voltage Vcc in volt
Rc1=1000.0          #collector resistance in ohm
Rc2=330.0           #collector resistance in ohm

#Calculations:
Iref=(Vcc-Vbe)/Rc1  #calculating reference current 
I0=Iref             #Output current is equal to Reference current 
V0=Vcc-Rc2*I0       #Calculating output volatge

Iref=Iref/10**-3    #calculating reference current

#Results:
print("Iref= %.1f mA"%Iref)
print("\nV0= %.3f V"%V0)

Iref= 11.3 mA

V0= 8.271 V

Example 2.3, Page No:40

In [3]:
#Variable Declaration
Vbe=0.6             #Voltage Vbe in volt
Vz=4.7              #Zener voltage in volt
Re=1000.0           #Emitter resistance in ohm

#Calculations:
Vre=Vz-Vbe          #Calculating voltage acrross emitter resistance

I=(Vre)/Re          #Calculating output current
I=I/10**-3          #Calculating output current

#Results
print("I=%.1f mA"%I)

I=4.1 mA

Example No. 2.4, Page No.: 42

In [4]:
#Variable Declaration:
import math
Vcc=20.0            #Vcc in volt
R1=19300.0          #resistance in ohm
Vbe=0.7             #Vbe voltage in Volt
Ic2=0.000005        #current in amperes
Vt=0.026            # Vt voltage in volt

#Calculations:
Ic1=(Vcc-Vbe)/R1                    #Calculating current through transistor Q1

R2=(Vt/Ic2)*math.log(Ic1/Ic2)       #Calculating value of R2 for desired current through transistor Q2

Ic1=Ic1/10**-3                      #Calculating current through transistor Q1
R2=R2/10**3                         #Calculating value of R2 for desired current through transistor Q2

#Results:
print("Ic1= %d mA"%Ic1)
print("\nR2= %.2f kohm"%R2)

Ic1= 1 mA

R2= 27.55 kohm

Example No.2.5, Page No: 44

In [5]:
#Variable Declaration:
Beta=100.0                  #Gain for transistor
R=20000.0                   #Resistance in ohm
Vcc=5.0                     #Volatage Vcc in volt
Vbe=0.6                     #Voltage Vbe in volt
N=3.0                       #Number of multiple current source

#Calculations:       
Iref=(Vcc-Vbe)/R            #Calculating reference current

Ic=Iref*(1+ 4/Beta)         #Calculating current through transistor Q
Ic1=Iref*(Beta)/(Beta+N+1)  #Calculating current through transistor Q1
Ic2=Iref*(Beta)/(Beta+N+1)  #Calculating current through transistor Q2
Ic3=Iref*(Beta)/(Beta+N+1)  #Calculating current through transistor Q3

Iref=Iref/10**-3            #Calculating Reference current
Ic1=Ic1/10**-3              #Calculating current through transistor Q1

#Results:
print("Iref= %.2f mA"%Iref)
print("\nIc1=Ic2=Ic3= %.3f mA"%Ic1)

Iref= 0.22 mA

Ic1=Ic2=Ic3= 0.212 mA

Example No.2.6, Page NO: 52

In [6]:
#Variable Declaration:
Iref=0.25*10**-3              #Reference current in amperes
Io=0.2*10**-3                 #Outpyt current in amperes
kn=20*10**-6                  #Transconductance in ampere per volt square
Vth=1.0                       #Threshold voltage in volt
Vgs2=1.752                    #Voltage Vgs2 in volt
lamb=0.0                      #Channel length modulation parameter
Vdd=5.0                       #Voltge Vdd in volt
Vss=0.0                       #voltage Vss in volt

#Calculations:
wbyltwo=Io/(kn*(Vgs2-Vth)**2)     #calculating width by length 2 ratio
Vdssat=Vgs2-Vth                   #Calculating voltage Vdssat
Vgs1=Vgs2                         #Volage Vgs1 is eqaul to Vgs2
wbylone=Iref/(kn*(Vgs2-Vth)**2)   #Calculating width by length 1 ratio
Vgs3=Vdd-Vss-Vgs1                 #Calculating Vgs3
wbylthr=Iref/(kn*(Vgs3-Vth)**2)   #calculating width by length 3 ratio

#Results:
print("W/L2= %.1f"%wbyltwo)
print("\nVds(sat)= %.3f V"%Vdssat)
print("\nW/L1= %.1f"%wbylone)
print("\nVgs3= %.3f V"%Vgs3)
print("\nW/L3= %.2f"% wbylthr)

W/L2= 17.7

Vds(sat)= 0.752 V

W/L1= 22.1

Vgs3= 3.248 V

W/L3= 2.47

Example No. 2.7, Page No: 75

In [7]:
#Variable Declaration:
cmrra=1000.0          #common mode rejection ratio
cmrrb=10000.0         #common mode rejection ratio 
v1a=100.0*10**-6      #input voltage in volt
v2a=-100.0*10**-6     #input voltage in volt
v1b=1100.0*10**-6     #input voltage in volt
v2b=900.0*10**-6      #input voltage in volt

#Calculations
#for first set
vida=v1a-v2a                   #Calculating differential volatge
vcma=(v1a+v2a)/2               #calculating common mode voltage
vic=0.0                        #Calculating common mode voltage
voa=vida*(1+vic/(cmrra*vida))  #Calculating Output voltage
voa=voa*10**6                  #Calculating output volatge

# for second set
vidb=v1b-v2b                   #Calculating differential volatge
vic=(v1b+v2b)/2                #calculating common mode voltage
vob=vidb*(1+vic/(cmrrb*vidb))  #Calculating Output voltage
vob=vob*10**6                  #Calculating Output voltage

#Results:
print("\nVo for second set= %.1f uV"%vob)
print("Vo for first set= %.1f uV"% voa)

#answer in textbook is wrong

Vo for second set= 200.1 uV
Vo for first set= 200.0 uV

Example No.2.8, Page No.76

In [8]:
#Variable Declaration:
Beta=100.0               #Gain
Vee=15.0                 #Voltage Vee in volt
Vcc=15.0                 #Voltage Vcc in volt
Vbe=0.7                  #Voltage Vbe in volt
Re=65.0*10**3            #Resistance in ohm
Rc=65.0*10**3            #Resistance in ohm
alpha=100.0/101.0        #Gain
Ve=-0.7                  #Voltage Ve in volt

#Calculations:
Ie=(Vee-Vbe)/(2*Re)      #Calculating emitter current
Ic=alpha*Ie              #Calculating collector current
Ib=Ic/Beta               #Calculating base current

Vc=Vcc-Ic*Rc             #Calculating collector volatge

Vce=Vc-Ve                #Calculating voltage between collector and emitter

Ie=Ie*10**6              #Calculating emitter current

Ic=Ic*10**6              #Calculating collector current

Ib=Ib*10**6              #Calculating base current

# by approximating, because Vee>>Vbe

Ieapprox=Vee/(2*Re)      #calculating emitter current by approximation
Ieapprox=Ieapprox*10**6  #calculating emitter current by approximation

#Results:
print('Ie= %.1f uA'%Ie)
print('\nIc= %.1f uA'%Ic)
print('\nIb= %.3f uA'%Ib)
print('\nVc= %.3f V'%Vc)
print('\nVce= %.3f V'%Vce)

print('\nIe (approx)= %.2f uA'%Ieapprox)

Ie= 110.0 uA

Ic= 108.9 uA

Ib= 1.089 uA

Vc= 7.921 V

Vce= 8.621 V

Ie (approx)= 115.38 uA

Example No.2.9, Page No.89

In [9]:
#Variable Declaration:
import math
Vdd=12.0                     #Voltage Vdd in volt
Vss=-12.0                    #Voltage Vss in volt
Iss=175.0*10**-6             #Current Iss in amperes
Rd=65.0*10**3                #resistance Rd in ohm
kn=3.0*10**-3                #Transconductance
Vth=1.0                      #Voltage Vth in volt

#Calculations:
Ids=Iss/2.0                  #Calculating Ids

Vgs=Vth + math.sqrt(Iss/kn)  #Calculating Vgs
 
Vds = Vdd- Ids*Rd + Vgs      #Calculating Vds

#Requirement for saturation
Vicmax= Vdd - Ids*Rd + Vth   #Calculating Vicmax

Ids=Ids*10**6                #Calculating Ids

#Results:
print('\nIds=%.1f uA'% Ids)
print('\nVgs=%.3f V'%Vgs)
print('\nVds=%.2f V'% Vds)
print('\nVicmax=%.2f V'% Vicmax)
print('\nRequirement of saturation for M1 \nfor non-zero Vic necessiates Vic <= 7.312 V')

Ids=87.5 uA

Vgs=1.242 V

Vds=7.55 V

Vicmax=7.31 V

Requirement of saturation for M1 
for non-zero Vic necessiates Vic <= 7.312 V