SUMMING AMPLIFIER/VOLTAGE ADDER - جامعة نزوى · ELEC207 LINEAR INTEGRATED CIRCUITS 23/02/2014 DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING SUMMING AMPLIFIER/VOLTAGE ADDER

ELEC207 LINEAR INTEGRATED CIRCUITS

23/02/2014

DEPARTMENT OF

ELECTRICAL & COMPUTER

ENGINEERING

SUMMING AMPLIFIER/VOLTAGE ADDER

It is based upon the standard Inverting

Operational Amplifier configuration that

can be used for combining multiple inputs

It amplify each individual input voltage and

produce an output voltage signal that is

proportional to the algebraic "SUM" of all

the individual input voltages

General output equation is given by


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DEPARTMENT OF


ENGINEERING

SCALING SUMMING AMPLIFIER

When the individual input resistors are "NOT" equal, it is a scaling summing

amplifier

General output equation is given by


23/02/2014

DEPARTMENT OF


ENGINEERING

EXAMPLE:

1. Find the output voltage of the circuit shown in the figure


23/02/2014

DEPARTMENT OF


ENGINEERING

SOLUTION:

1. Find the output voltage of the circuit shown in the figure


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DEPARTMENT OF


ENGINEERING

DIFFERENTIAL AMPLIFIER

Differential amplifiers amplify the difference between two voltages making this type

of operational amplifier circuit a Subtractor

By connecting one voltage signal onto one input terminal and another voltage

signal onto the other input terminal, the resultant output voltage will be proportional

to the "Difference" between the two input voltage signals of V1

and V2

If all the resistors are of the same value, i.e R1

= R2

= R3

= R4

then the circuit will

become a Unity Gain Differential Amplifier and the voltage gain of the amplifier will

be exactly one or unity. Then the output expression would simply be

Vout

= V2- V

1

Va

Vb


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DEPARTMENT OF


ENGINEERING

DIFFERENTIAL AMPLIFIER

Va

Vb


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DEPARTMENT OF


ENGINEERING

INSTRUMENTATION AMPLIFIER

Instrumentation amplifier is a kind of differential amplifier with additional input

buffer stages. The addition of input buffer stages makes it easy to match

(impedance matching) the amplifier with the preceding stage

Commonly used in industrial test and measurement application


23/02/2014

DEPARTMENT OF


ENGINEERING

ANALYSIS OF INSTRUMENTATION AMPLIFIER

The proof for instrumentation amplifier

transfer function starts with Super position

theorem.

Case 1: (Figure 1a)

Make V12

= 0 by connecting U2

input to

ground and calculate for Vout1

Figure 1a


23/02/2014

DEPARTMENT OF


ENGINEERING

ANALYSIS OF INSTRUMENTATION AMPLIFIER

Case 2: (Figure 1b)

Make V21

= 0 by connecting U1

input to

ground and calculate for Vout2

Figure 1b

Final Equation: Vout

=Vout1

+Vout2


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DEPARTMENT OF


ENGINEERING

COMPARATOR

Voltage comparator is a circuit which compares two voltages and switches the output

to either high or low state depending upon which voltage is higher.

Non-inverting comparator

Reference voltage is applied to the

inverting input and the voltage to be

compared is applied to the non inverting

input

Whenever the voltage to be compared (Vin)

goes above the reference voltage , the

output of the op-amp swings to positive

saturation (V+) and When V

ingoes below

reference voltage, the output swings to

negative saturation(V-)

Vref

Vin>V

ref, V

out=V

+

Vin


25/02/2014

DEPARTMENT OF


ENGINEERING

Inverting comparator

Reference voltage is applied to the non-

inverting input and the voltage to be

compared is applied to the inverting input

Whenever the voltage to be compared (Vin)

goes above the reference voltage , the

output of the op-amp swings to negative

saturation (V-) and When V

ingoes below

reference voltage, the output swings to

positive saturation(V+)

COMPARATOR

Vref

Vin>V

ref, V

out=V

-

Vin


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DEPARTMENT OF


ENGINEERING

Non-inverting and Inverting Comparator waveforms

Non-inverting Comparator Input and

Output Waveforms

Inverting Comparator Input and

Output Waveforms


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DEPARTMENT OF


ENGINEERING

SCHMITT TRIGGER

Designed with a positive feedback and hence will have a regenerative action which

will make the output switch levels. Hence it is also called a regenerative

comparator circuit

The use of positive voltage feedback instead of a negative feedback, aids the

feedback voltage to the input voltage

The purpose of the schmitt trigger is to convert any regular or irregular shaped

input waveform into a square wave output voltage or pulse. Thus, it can also be

called a squaring circuit


25/02/2014

DEPARTMENT OF


ENGINEERING

SCHMITT TRIGGER

Applying Super position Theorem at V1,

For switching the output from Vsat+

to Vsat-

, V1=0 V1

When Vout = Vsat-, value of Vin to switch output state from Vsat- to Vsat+ is

When Vout = Vsat+, value of Vin to switch output state from Vsat+ to Vsat- is


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DEPARTMENT OF


ENGINEERING

SCHMITT TRIGGER

Hysteresis width VH

is

Vsat+

Vsat-

Hysteresis Loop


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DEPARTMENT OF


ENGINEERING

EXAMPLE

1. For the Schmitt trigger shown below calculate the upper threshold voltage, lower

threshold voltage and the hysteresis width if the saturation voltages are 12V.

1k

3k


25/02/2014

DEPARTMENT OF


ENGINEERING

SOLUTION

1. For the Schmitt trigger shown below calculate the upper threshold voltage, lower

threshold voltage and the hysteresis width if the saturation voltages are 12V.

1k

3k


25/02/2014

DEPARTMENT OF


ENGINEERING

DIFFERENCE BETWEEN COMPARATOR AND SCHMITT TRIGGER

Comparator change its state when the voltage exceeds a threshold and return to

the initial state when the voltage drops below this threshold.

Schmitt trigger change its state when the voltage exceed a threshold and will not

return to the initial state until the voltage drops at a certain value below the initial

threshold.

Comparator Output Schmitt trigger Output

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SUMMING AMPLIFIER/VOLTAGE ADDER - جامعة نزوى · ELEC207 LINEAR INTEGRATED CIRCUITS 23/02/2014 DEPARTMENT OF ELECTRICAL & COMPUTER ENGINEERING SUMMING AMPLIFIER/VOLTAGE ADDER