1. Analogue Electronic 2 EMT 212
Chapter 1
Operational Amplifier By
En. Rosemizi B. Abd Rahim

2. 1.0 Operational Amplifier
1.1 Introduction
1.2 Ideal Op-Amp
1.3 Op-amp input modes
1.4 Op-amp Parameters
1.5 Operation
Single-mode
Differential-mode
Common-mode operation
1.6 Op-Amps basics
1.7 Datasheet

3. 1.1 Introduction Typical IC packages
IC packages placed on circuit board

4. 1.1 Introduction Uses of Op-Amp
To provide voltage amplitude changes (amplitude and polarity)
Comparators
Oscillators
Filter circuits
Instrumentation circuits

5. 1.1 Introduction Definition
The operational amplifier or op-amp is a circuit of components integrated into one chip.
A typical op-amp is powered by two dc voltages and has an inverting(-) and a non-inverting input (+) and an output.
Op-amps were used to model the basic mathematical operations ; addition, subtraction, integration, differentiation etc in electronic analog computers.

6. 1.1 Introduction Two Power Supply +V : Positive PS -V : Negative PS
One Output Terminal
Op-amp schematic symbol
Two Input Terminal
Inverting input
Non-inverting input

7. 1.2 Ideal Op-Amp
Practical Op-Amp
Ideal Op-Amp

8. 1.2 Ideal Op-Amp Properties Practical Op-Amp Ideal Op-Amp
input impedance 500k-2M
output impedance 
open-loop gain (20k to 200k)
Bandwidth limited (a few kHz)
noise contribution
Non-zero DC output offset
Infinite input impedance
Zero output impedance
Infinite open-loop gain
Infinite bandwidth
Zero noise contribution
Zero DC output offset
Both differential inputs stick together

9. 1.2 Ideal Op-Amp Infinite Input Impedance
Input impedance is measured across the input terminals
It is the Thevenin resistance of the internal connection between the two input terminals.
Input impedance is the ratio of input voltage to input current.
Zi=(Vi/Ii)
When Zi is infinite, the input current is zero.
the op amp will neither supply current to a circuit nor will it accept current from any external circuit.
In real, the resistance is 500k to 2M

10. 1.2 Ideal Op-Amp Zero Output Impedance
Looking back into the output terminal, we see voltage source with an internal resistance.
The internal resistance of the op-amp is op-amp output impedance
This internal resistance is in series with the load, reducing the output voltage available to the load
Real op-amps have output impedance in the range  .

11. 1.2 Ideal Op-Amp Infinite Open-Loop Gain
Open-Loop Gain, A is the gain of the op-amp without feedback.
In the ideal op-amp, A is infinite
In real op-amp is (20k to 200k)

12. 1.2 Ideal Op-Amp Infinite Bandwidth
The ideal op-amp will amplify all signals from DC to the highest AC frequencies
In real op-amps, the bandwidth is rather limited
This limitation is specified by the Gain-Bandwidth product, which is equal to the frequency where the amplifier gain becomes unity
Some op-amps, such as 741 family, have very limited bandwidth up to a few kHz

13. 1.2 Ideal Op-Amp Zero Noise Contribution
in an ideal op amp, all noise voltages produced are external to the op amp. Thus any noise in the output signal must have been in the input signal as well.
the ideal op amp contributes nothing extra to the output noise.

14. 1.2 Ideal Op-Amp Zero Output Offset
The output offset voltage of any amplifier is the output voltage that exists when it should be zero.
The voltage amplifier sees zero input voltage when both inputs are grounded. This connection should produce a zero output voltage.
If the output is not zero then there is said to be an output voltage present.
In the ideal op amp this offset voltage is zero volts, but in practical op amps the output offset voltage is nonzero.

15. 1.2 Ideal Op-Amp Both Differential Inputs Stick Together
this means that a voltage applied to one inverting inputs also appears at the other non-inverting inputs.
If we apply a voltage to the inverting input and then connect a voltmeter between the non-inverting input and the power supply common, then the voltmeter will read the same potential on non-inverting as on the inverting input.

16. 1.3 Op-Amp input Modes Single-Ended input mode
input signal is connected to one input and the other input is grounded.
input signal at +ve terminal  output same polarity as the applied input signal
input signal at –ve terminal  output opposite in phase to the applied input signal

17. 1.3 Op-Amp input Modes Differential mode input
two out-of-phase signals are applied with the difference of the two amplified and produced at the output.

18. 1.3 Op-Amp input Modes Common mode input
two signals of same phase, frequency, and amplitude are applied to the inputs which results in no output (signals cancel). Practically, a small output signal will result.
This is called common-mode rejection. This type of mode is used for removal of unwanted noise signals.

19. 1.4 Op-Amp Parameters Common-Mode Rejection Ratio (CMRR)
The ability of amplifier to reject the common-mode signals
Ratio of open-loop gain to common-mode gain
The higher the CMRR, the better
open-loop gain is high and common-mode gain is low.

20. 1.4 Op-Amp Parameters Common-Mode Input Voltage
The range of input voltages which, when applied to the both inputs, will not cause clipping or other output distortion.
Input Offset Voltage
The differential dc voltage required between the inputs to force the output to zero volts.
Range between 2 mV

21. 1.4 Op-Amp Parameters Input Bias Current
The dc current required by the inputs of the amplifier to properly operate the first stage.
Is the average of both input currents

22. 1.4 Op-Amp Parameters Input Impedance
Is the total resistance between the inverting and non-inverting inputs.
Differential input impedance is measured by the changes of differential input voltage over changes of bias current.
Common-mode input impedance is measured by the changes of common-mode input voltage over changes of bias current.

23. 1.4 Op-Amp Parameters Input Offset Current
Is the different of input bias currents
Input offset current
error
offset voltage

24. 1.4 Op-Amp Parameters Output Impedance
Is the resistance viewed from the output terminal of the op-amp.

25. 1.4 Op-Amp Parameters Slew Rate
Is the maximum rate of change of the output voltage in response to a step input voltage.

26. 1.4 Op-Amp Parameters
Example
Determine the slew rate

27. 1.5 Operation Differential Amplifier Circuit
Basic amplifier circuit
If an input signal is applied to either input with the other input is connected to ground, the operation is referred to as ‘single-ended.’
If two opposite-polarity input signals are applied, the operation is referred to as ‘double-ended.’
If the same input is applied to both inputs, the operation is called ‘common-mode.’

28. 1.5 Operation Differential Amplifier Circuit DC Analysis
DC bias of differential amplifier circuit
DC Analysis

29. 1.5 Operation Differential Amplifier Circuit Example Solution
Calculate the dc voltages and currents

30. 1.5 Operation Differential Amplifier Circuit AC Analysis Single-Ended
AC equivalent of differential amplifier circuit
AC connection of differential amplifier

31. 1.5 Operation Differential Amplifier Circuit AC Analysis Single-Ended
AC equivalent circuit
connection to calculate Av1 = Vo1 / Vi1

32. 1.5 Operation Differential Amplifier Circuit
AC Analysis Single ended
KVL
Scan figure & 10.15
Partial circuit for calculating Ib

33. 1.5 Operation Differential Amplifier Circuit Example Solution
Calculate the single-ended output voltage Vo1

34. 1.5 Operation Differential Amplifier Circuit
AC Analysis Double ended
A similar analysis can be used to show that for the condition of signals applied to both inputs, the differential voltage gain magnitude is

35. 1.5 Operation Differential Amplifier Circuit AC Analysis - Common-mode
Common-mode connection

36. 1.5 Operation
Differential Amplifier Circuit
AC Analysis - Common-mode

37. 1.6 Op-Amp Basics Basic Op-Amp Op-amp equivalent circuit practical
ideal

38. 1.6 Op-Amp Basics Basic Op-Amp - Constant-gain multiplier
input voltage at minus output voltage opposite in phase

39. 1.6 Op-Amp Basics Basic Op-Amp - Constant-gain multiplier
Op-amp ac equivalent circuit

40. 1.6 Op-Amp Basics Basic Op-Amp - Constant-gain multiplier
Ideal Op-amp equivalent circuit
Redrawn equivalent circuit

41. 1.6 Op-Amp Basics Basic Op-Amp - Constant-gain multiplier
Using Superposition theorem
i) V1 only (set –AvVi =0)
ii) –AvVi only (set V1 =0)
Shown that the ratio i/o depends only on the value of Rf and R1

42. 1.6 Op-Amp Basics Basic Op-Amp - Unity Gain If Rf = R1
Shown that the output voltage equal to input voltage with 180º phase inversion.

43. 1.6 Op-Amp Basics Basic Op-Amp - Constant Magnitude Gain If Rf = 10R1
Shown that the output voltage equal to 10x input voltage with 180º phase inversion.

44. 1.7 Data Sheet LM741

45. 1.7 Data Sheet LM741

46. 1.7 Data Sheet LM741

47. 1.7 Data Sheet LM741

48. 1.7 Data Sheet LM741

49. 1.7 Data Sheet LM741