Topic 3 - Opamp2student

8/13/2019 Topic 3 - Opamp2student

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Topic 3Operational Amplifier

(Op- Amp)

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COURSE LEARNING OUTCOMES

(CLO)

CLO1. explain correctly the principles of electronic

circuits by using block diagram or circuit diagram(C4)

CLO2. conduct the construction of electronic

circuits application during practical works based on

the theory and principle operation of the circuits.

(P4)CLO3. deliver an oral presentation to display good

communication skills. (A2)

2


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LEARNING OUTCOMES

Upon completion of this topic students should be able to:

Explain the general op-amp circuit design3.1

Explain the differential amplifier3.2

3.3

3.4

3.5

Draw complimentary and push pull amplifier

Explain the ideal characteristics of op-amp

Construct the op-amp configurations

3


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Operational Amplifier(Op- Amp)

1) What is the meaning of operational

amplifier?

2) Symbol of operational amplifier.3) Block diagram of operational amplifier.


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Operational Amplifier

An op amp is a high voltage gain, DC amplifier with high input

impedance, low output impedance, and differential inputs.Positive input at the non-inverting input produces positive output,

positive input at the inverting input produces negative output.


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Block diagram of DC op amp


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TERM DEFINITION


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1 . Input bias current

Op-amps have a small current called the

Input Bias Current, IBias.

IBias

is a DC current flowing in or out of the

input terminals

It is defined as the average of the currents

at the two terminals. IBias

is really the Base

or Gate current of the input transistors.


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2. Input Offset Current

Different in IBias between the two input

transistor in op amp.

IBias (inverting)

and IBias (non-inverting)

are not

equal

Input offset current = IBias (inverting)- IBias

(non - inverting)


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3. Input Offset Voltage

The di f ference in inpu t vo l tages necessary to

br ing the ou tpu t to zero is cal led the inpu t

offs et vo ltage, VOS.


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4. Common Mode Gain

Gain when both input

terminal have same signal.

When Vin = 0, Vo = 0


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5. Common Mode Rejection Ratio

(CMRR)

is a performance specification of an

electronic circuit component.

Normally Common mode gain


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Question

1) What is the meaning of input bias

current?


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Question

2) What is the meaning of input offset

voltage?


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Operational Amplifier

configurations

The second most basic format of an op

amp circuit is the non inverting amplifier.

This configuration uses negative feedback

to stabilize the voltage gain. Used toincrease the amplitude of the input signal.

Circuit is as follows;


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Non inverting amplifier

Using the formula to

calculate the output

voltage of a potential

divider network, wecan calculate the

closed-loop voltage

gain (Av) of the Non-

inverting Amplifieras follows


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Then the closed loop voltage gain of a Non-inverting

Amplifieris given as:


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Phase relationship between input and output voltage of the non

inverting amplifier


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Example

From the diagram,

calculate the value of

Vo if 1V is applied to

the circuit.


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Answer


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Question 1

From figure 1,

calculate the values

of voltage gain if

R2= 12KandRf = 50K.

Figure 1


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Question 2

Calculate the values

of V1 if

Vout = 5V,

R2= 100Kand

Rf = 50K


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Question 3

If non inverting op-amp produces a gain of

Rf/Ra, draw the input-output connection of

the op-amp


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Question 4

By referring to question 3, given a gain of

10 for the op-amp, the input voltage 0.24V,

what is the output voltage?


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Inverting Amplifier

Used to amplify and phase reverse the input signal. Inverting input is a

virtual earth.


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Inverting Amplifier

CIRCUIT ANALYSIS


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Inverting Amplifier


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Inverting Amplifier Then, the Closed-Loop Voltage Gainof an Inverting Amplifier is given as.

and this can be transposed to give Vout as :


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Inverting Amplifier

Phase relationship between input and output voltage of the inverting

amplifier


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Question 5

From figure 2,

calculate the values

of voltage gain if

Rin= 12KandRf = 50K

Figure 2


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Question 6

Calculate the values

of V1 if

Vout = 5V,

Rin= 100Kand

Rf = 50K


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Question 7

If an inverting op-amp produces a gain of

Rf/Ra, draw the input-output connection of

the op-amp


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Question 8

By referring to question 7, given a gain of

10 for the op-amp, the input voltage 0.24V,

what is the output voltage?


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Summing amplifier

Used to mix the input signals


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Summing amplifier

Circuit Analysis:


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Subtractor

Used to substract input signal.
http://localhost/var/www/apps/conversion/tmp/scratch_5/SUBSTRACT.docx


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Subtractor

Circuit Analysis


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Subtractor


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Subtractor


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Subtractor


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Differentiator
http://localhost/var/www/apps/conversion/tmp/scratch_5/DIFFERENTOR.docx


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Differentiator

Circuit Analysis:

Since the node voltage of the operational amplifier at its inverting input

terminal is zero, the current, i flowing through the capacitor will be

given as;

= Ic


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Differentiator


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Integrator
http://localhost/var/www/apps/conversion/tmp/scratch_5/INTERGRATOR.docx


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Integrator

Integrator Amplifieris an operational amplifier circuit

that performs the mathematical operation of Integration.

The integrator amplifier acts like a storage element that

"produces a voltage output which is proportional to the

integral of its input voltage with respect to time"


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Integrator

Circuit analysis

The voltage across the capacitor is output Vout therefore: -Vout = Q/C. If the capacitor is charging and discharging, the rate of

charge of voltage across the capacitor is given as:


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Integrator

But dQ/dtis electric current and since the

node voltage of the integrating op-amp at

its inverting input terminal is zero, X = 0,

the input current I(in) flowing through theinput resistor, Rin is given as:


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Integrator

The current flowing through the feedback capacitor C is given as:


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Integrator

Assuming that the input impedance of the

op-amp is infinite (ideal op-amp), no

current flows into the op-amp terminal.

Therefore, the nodal equation at theinverting input terminal is given as:


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Integrator


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Integrator

From which we derive an ideal voltage output for the Integrator

Amplifieras:

To simplify the math's a little, this can also be re-written

as:


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Comparator
http://localhost/var/www/apps/conversion/tmp/scratch_5/COMPARATOR.docx


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Comparator

The Comparator

an Open-Loop Device

When applying a comparator, the designer compares thevoltage level at two inputs. The comparator produces adigital output that corresponds to the inputs:

If the voltage on the noninverting (+) input is greaterthan the voltage on the inverting (-) input, the output ofthe comparator goes to low impedanceon for opencollector / drain outputs.

If the voltage on the noninverting (+) input is less than

the voltage on the inverting (-) input, the output of thecomparator goes to high impedance off for opencollector / drain outputs


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Comparator


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Comparator


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1.The ideal Op-Amp
http://localhost/var/www/apps/conversion/tmp/scratch_5/idealopamp.docx


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Test 1

Tolong baca dan fahami !!!

type of regulator cct, bridge rect.draw and

operation, Block oscillator, calculate harley

freq., characteristic of ideal opamp. Non-inverting.


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THE END

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Operational amplifier


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Operational amplifier

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Topic 3 - Opamp2student