## Ex1.1:Pg-10¶

In [1]:
#Ex 1.1
import math
VDD=1.8;#V
IREF=50;#micro A
IO=IREF;#micro A
L=0.5;#micro m
W=5;#micro m
Vt=0.5;#V
Kn_dash=250;#micro A/V**2
VGS=math.sqrt(IO/(1/2.0*Kn_dash*(W/L)))+Vt;#V
print VGS," is the Value of VGS(V) "
R=(VDD-VGS)/(IREF*10**-6);#ohm
print R/1000," is the Value of R(kohm) "
VDS2=VGS-Vt;#V
VO=VDS2;#V
print VO," is the Lowest value of VO(V) "

0.7  is the Value of VGS(V)
22.0  is the Value of R(kohm)
0.2  is the Lowest value of VO(V)


## Ex1.3:Pg-12¶

In [4]:
#Ex 1.3

VDD=1.8;#V
Vt=0.6;#V
mpCox=100;#a A/V**2
IREF=80;#micro A
VOmax=1.6;#V
VSG=VDD-VOmax+Vt;#V
VGS=-VSG;#V
VS=VDD;#V
VG=VGS+VS;#V
R=VG/(IREF*10**-6);#ohm
ID=IREF;#micro A
WbyL=2*ID*10**-6/(mpCox*10**-6)/(VGS+Vt)**2;#unitless
print VGS,"= Value of VGS(V) "
print VG,"= Value of VG(V) "
print R/1000,"= Value of R(kohm) "
print WbyL,"= W/L ratio "

-0.8 = Value of VGS(V)
1.0 = Value of VG(V)
12.5 = Value of R(kohm)
40.0 = W/L ratio


## Ex1.4:Pg-19¶

In [7]:
#Ex 1.4

Beta=80;#unitless
print "IREF=IC1+IC1/Beta+IO/Beta)"
print "IO/IREF=m implies IC1=IO/m as IC1=IREF"
print "IREF=IO*(1/m+1/m/Beta+1/Beta)"
print "IO/IREF=m/(1+1/Beta+m/Beta)"
print "IO/IREF=m*(1-5/100)"#for large Beta
m=(1/(1-5.0/100)-1)*Beta-1;#Current transfer ratio
print round(m,2)," is Largest current transfer ratio "

IREF=IC1+IC1/Beta+IO/Beta)
IO/IREF=m implies IC1=IO/m as IC1=IREF
IREF=IO*(1/m+1/m/Beta+1/Beta)
IO/IREF=m/(1+1/Beta+m/Beta)
IO/IREF=m*(1-5/100)
3.21  is Largest current transfer ratio


## Ex1.7:pg-37¶

In [63]:
#Ex 1.7

Beta=80;#untless
print "g8=IC1+IC1/Beta+IO/Beta"
print "IO/IREF=m implies IC1=IO/m as IC1=IREF"
print "IREF=IO*(1/m+1/m/Beta+1/Beta"
print "IO/IREF=m/(1+1/Beta+m/Beta"
print "IO/IREF=m*(1-5/100)"#for large Beta
m=(1/(1-5.0/100)-1)*Beta-1;#Current transfer ratio
print round(m,2),"Largest current transfer ratio  "

g8=IC1+IC1/Beta+IO/Beta
IO/IREF=m implies IC1=IO/m as IC1=IREF
IREF=IO*(1/m+1/m/Beta+1/Beta
IO/IREF=m/(1+1/Beta+m/Beta
IO/IREF=m*(1-5/100)
3.21 Largest current transfer ratio


## Ex1.9:Pg-39¶

In [10]:
#Ex 1.9

Beta=20.0;#unitless
IObyIREF=1/(1+2/Beta);#Current gain
print round(IObyIREF,2)," is Current gain  "

0.91  is Current gain


## Ex1.10:Pg-39¶

In [13]:
#Ex 1.10

IREF=2;#mA
IO=IREF;#mA
VA2=90.0;#V
Vo1=1.0;#V
Vo2=10.0;#V
ro2=VA2/IO;#kohm
delVO=Vo2-Vo1;#V
delIO=delVO/ro2;#mA
Change=delIO/IO*100;#%
print Change," % is Change in Io "

10.0  % is Change in Io


## Ex1.11:Pg-40¶

In [18]:
#Ex 1.11

import math
VBE3=0.7;#V
VBE1=0.7;#V
IREF1=100.0;#micro A
IC1=IREF1;#micro A
IREF2=1.0;#mA
IC2=IREF2;#mA
Beta=200.0;#unitless
#IC2/IC1=(IS*exp(VBE2/VT))/(IS*exp(VBE1/VT))
VT=26.0;#mV
deltaVBE=VT*10**-3*math.log(IC2/IC1);#V(deltaVBE=VBE2-VBE1)
deltaVx=2*deltaVBE;#V
IO=IREF1/(1+2.0/(Beta**2+Beta));#micro A
delIO=IC1-IO;#micro A
Change=delIO/IO*100;#%
print round(Change,4)," % is Change in Io"

0.005  % is Change in Io


## Ex1.12:Pg-41¶

In [22]:
#Ex 1.12

Iout=8;#micro A
VBE=0.7;#V
VCC=20.0;#V
Beta=80.0;#unitless
IREF=Iout*(1+2/Beta);#micro A
print IREF," is Reference current in micro A : "
R=(VCC-VBE)/(IREF);#Mohm
print round(R,2)," is Resistance in Mohm "

8.2  is Reference current in micro A :
2.35  is Resistance in Mohm


## Ex1.13:Pg-42¶

In [25]:
#Ex 1.13

Iout=1;#mA
VBE=0.7;#V
VCC=30.0;#V
Beta=100.0;#unitless
IREF=Iout*(1+2/Beta);#mA
print IREF," is Reference current in (mA) "
R=(VCC-VBE)/(IREF);#kohm
print round(R,1),"is Resistance in (kohm) "

1.02  is Reference current in (mA)
28.7 is Resistance in (kohm)


## Ex1.14:Pg-42¶

In [28]:
#Ex 1.14

Iout=0.5;#mA
VBE=0.7;#V
VCC=5.0;#V
Beta=50.0;#unitless
IREF=Iout*(1+2/Beta);#mA
print IREF," is Reference current in (mA) "
R=(VCC-VBE)/(IREF);#kohm
print round(R,3)," is Resistance in (kohm) "

0.52  is Reference current in (mA)
8.269  is Resistance in (kohm)


## Ex1.15:Pg-43¶

In [31]:
#Ex 1.15

Iout=8;#micro A
VBE=0.7;#V
VCC=20.0;#V
Beta=100.0;#unitless
IREF=Iout*(1+2/Beta/(Beta+1));#micro A
print round(IREF,2)," is Reference current in (micro A)  "
R=(VCC-2*VBE)/(IREF);#Mohm
print round(R,2)," is Resistance in (Mohm) "

8.0  is Reference current in (micro A)
2.32  is Resistance in (Mohm)


## Ex1.16:Pg-45¶

In [33]:
#Ex 1.16

Beta=120;#unitless
VBE=0.7;#V
VCC=10.0;#V
R=5.6;#kohm
#IREF=IC1+I1;as Beta>>1
#I1=IC2+IB3;as Beta>>1
IREF=(VCC-VBE)/R;#mA
#IREF=IC*(2+1/Beta) or IREF=2*IC;as Beta>>1
IC=IREF/2;#mA
Iout=IC;#mA
print round(Iout,2),"is Iout for the circuit in (mA) "

0.83 is Iout for the circuit in (mA)


## Ex1.17:Pg-45¶

In [40]:
#Ex 1.17
import math
Iout=6;#micro A
IREF=1.2;#mA
VBE2=0.7;#V
VT=26.0;#mV
VCC=20.0;#V
Beta=120;#unitless
R=(VCC-VBE2)/IREF;#kohm
IC2=(IREF-Iout/Beta)/(1+1/Beta);#mA
RS=VT/Iout*math.log(IC2*1000/Iout);#kohm
print int(R),"Kohm and ",round(RS,2),"kohm are the Values of resistance R & Rs for widlar current source design"

16 Kohm and  22.96 kohm are the Values of resistance R & Rs for widlar current source design


## Ex1.18:Pg-47¶

In [49]:
#Ex 1.18

import math
IREF=1;#mA
IO2=20.0;#micro A
IO3=40.0;#micro A
VBE1=0.7;#V
VT=26;#mV
VCC=10;#V
VEE=-VCC;#V
R=(VCC-VBE1-VEE)/IREF;#kohm
RE2=VT*10**-3/(IO2*10**-6)*math.log((IREF*10**-3)/(IO2*10**-6));#ohm
RE2=RE2/1000;#kohm
RE3=VT*10**-3/(IO3*10**-6)*math.log((IREF*10**-3)/(IO3*10**-6));#ohm
RE3=RE3/1000;#kohm
print R,", ",round(RE2,3),"and ", round(RE3,2)," are Values of resistance R, RE2 & RE3 for widlar current source design in kohm "
VBE2=VBE1-RE2*IO2*10**-3;#V
VBE3=VBE1-RE3*IO3*10**-3;#V

print round(VBE2,3),"and",round(VBE3,3)," are Values of VBE2 & VBE3 in V "

19.3 ,  5.086 and  2.09  are Values of resistance R, RE2 & RE3 for widlar current source design in kohm
0.598 and 0.616  are Values of VBE2 & VBE3 in V


## Ex1.19:Pg-48¶

In [52]:
#Ex 1.19

Beta=100.0;#unitless
VBE=0.715;#V
VEE=10.0;#V
R=5.6;#kohm
IREF=(VEE-VBE)/R;#mA
IC1=IREF/(1+2/Beta);#mA
print round(IC1,2)," is Collector current in each transistor is equal as all are identical. It in (mA) "
IRC=3*IC1;#mA
print round(IRC,2),"is Current through resistance Rc in (mA)  "
# the answer is slightly different in textbook due to approximation

1.63  is Collector current in each transistor is equal as all are identical. It in (mA)
4.88 is Current through resistance Rc in (mA)


## Ex1.20:Pg-49¶

In [56]:
#Ex 1.20

Vout=5.0;#V
Beta=180.0;#unitless
VBE=0.7;#V
VEE=10.0;#V
Vout=5;#V
R1=22.0;#kohm
R2=2.2;#kohm
IREF=(VEE-VBE)/R1;#mA
IC=(IREF-VBE/R2)/(1+2/Beta);#mA
IC1=IC*1000;#micro A(as VBE1=VBE2 IC1=IC2)
IC2=IC*1000;#micro A
print round(IC2,2),",",round(IC1,2)," are Current IC1 & IC2 in micro A  "
RC=(VEE-Vout)/(IC1*10**-3);#kohm
print round(RC,2),"is Value of Rc in (kohm) "

#Answer is different in the textbook due to approximation

103.4 , 103.4  are Current IC1 & IC2 in micro A
48.36 is Value of Rc in (kohm)


## Ex1.21:Pg-51¶

In [62]:
#Ex 1.21

AQ2byA1=0.5;
AQ3byA1=0.25;
AQ4byA1=0.125;
VBE=0.7;#V
VCC=15.0;#V
R=20.0;#kohm
IC1=(VCC-VBE)/R;#mA
IC2=IC1*AQ2byA1;#mA
IC3=IC1*AQ3byA1;#mA
IC4=IC1*AQ4byA1;#mA
print round(IC2,4),",",round(IC3,3),"and",round(IC4,3),"are the Values of current IC2, IC3 & IC4 in (mA)  "
#Value of IC4 is displayed wrong in the textbook.

0.3575 , 0.179 and 0.089 are the Values of current IC2, IC3 & IC4 in (mA)