Chapter 2 : Operational Amplifier Fundamentals

example 2.1, Page No. 59

In [5]:
# Input bias and input offset current

import math
#Variable declaration
Ib1 = 18*10**-6             # base current of transistor 1
Ib2 = 22*10**-6             # base current of transistor 2

#Calculations
#(i)
Ib = (Ib1+Ib2)/2
#(ii)
Iios = abs(Ib1-Ib2)

#Result
print("(i)  Input bias current = %d micro-A\n(ii) Input offset current = %.0f micro-A"%(Ib*10**6,Iios*10**6))

(i)  Input bias current = 20 micro-A
(ii) Input offset current = 4 micro-A

example 2.2, Page No. 65

In [11]:
#Maximum frequency of operation

import math
#Variable declaration
Vin = 3.0               # input voltage
sr = 0.5*10**6          # slew rate in V/Sec

#Calculations
Vm = Vin/2
fm = sr/(2*math.pi*Vm)
fm = fm /1000 

#Result
print("Maximum frequency of operation is %.3f kHz"%(math.floor(fm*1000)/1000))

Maximum frequency of operation is 53.051 kHz

example 2.3, Page No. 65

In [15]:
# Slew rate 

import math
#Variable declaration
Icq = 15*10**-6         # Maximum op-amp current 
C = 35*10**-12          # equivalent capacitance
V = 12.0                # input voltage 

#Calculations
S = Icq/C
S = S/10**6

#Result
print("Slew rate = %.4f V/micro-sec"%(math.floor(S*10**4)/10**4))

Slew rate = 0.4285 V/micro-sec

example 2.4, Page No. 66

In [20]:
#Slew rate and maximum possible frequency of input

import math
# Variable declaration
Icq = 10*10**-6             # maximum op-amp current
C = 33*10**-12              # equivalent capacitance
V = 12                      # peak value of input voltage


#Calculations
S = Icq/C
fm = S/(2*math.pi*V)

#Result
print("Slew rate = %.3f V/micro-sec\nfm        = %.3f kHz"%(S/10**6,fm/1000))

Slew rate = 0.303 V/micro-sec
fm        = 4.019 kHz

example 2.5, Page No. 66

In [2]:
# Common mode rejection ratio(refere to fig 2.24)

import math
#Variable declaration
R1 = 1000.0            # resistance 1
R2_1_E = 90000.0       # resistance R2(1-E)
R2 = 100000.0          # resistance R2

#Calculations
Aid = R2/R1
E = 1-(R2_1_E/R2)
Acm = R2*E/(R1+R2)
CMRR = Aid/Acm
CMRR = 20*math.log10(CMRR)

#Result
print("CMRR = %d dB"%CMRR)

CMRR = 60 dB