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ECD II PresentationOP-AMP Applications
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• Presented by Group 12
• Aroosa• Sheher• Sidra Ali
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Introduction
What is OP-AMP
Mathematics of OP-AMP
Characteristics of OP-AMP
Ideal OP-AMP
Types of OP-AMP
Applications of OP-AMP
Description of OP-AMP applications
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What is Op Amp
• An Operational Amplifier (Op-Amp) is an integrated circuit that uses external voltage to amplify the input through a very high gain
What an Op-Amp lookslike to a lay-person
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What is an Op-Amp? – The Surface• .
• What an Op-Amp lookslike to an engineer
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What is an Op-Amp? – The Inside• The actual count varies, but an Op-Amp contains
several Transistors, Resistors, and a few Capacitors and Diodes.
• For simplicity, an Op-Amp is often depicted as this:
Inverting
Input
Non-
Inverting
Input
Positive
Power
Supply
Negative
Power
Supply
Output
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Mathematics of the Op-Amp
• The gain of the Op-Amp itself is calculated as:
G = Vout/(V+ – V-)
• The maximum output is the power supply voltage
• When used in a circuit, the gain of the circuit (as opposed to the op-amp component) is:
Av = Vout/Vin
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Op-Amp Characteristics
• Open-loop gain G is typically over 9000
• But closed-loop gain is much smaller
• Rin is very large (MΩ or larger)
•Rout is small (75Ω or smaller)
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Ideal Op-Amp Characteristics
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Types of Op-Amps
o Inverting
oNon-inverting
oSumming amplifier
oThe voltage follower
o Integrator
oDifferentiator
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Applications of Op-Amps
• Comparator
• Integration and differentiation
• Charge amplifier
• Capacitance multiplier
• Oscillators
• Filters
• Audio and video preamplifiers and buffers
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Applications of Op-Amps
• Voltage regulator and current regulator
• Digital-to-analog converter
• Voltage clamps
• Oscillators and waveform generators
• Analog computer
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Comparator
• Compares two voltages or currents and outputs a digital signal indicating which is larger.
• Two analog input terminals and one Output
.
• The op-amp's output voltage is limited by the supply voltage.
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Integration
•Performs the mathematicaloperation of Integration.
• Output signal is determined by the length of time a voltage is present at its input as the current through the feedback loop charges or discharges the capacitor as the required negative feedback occurs through the capacitor.
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Differentiation
• Amplifies the difference between two voltages but does not amplify the particular voltages.
=Common-mode gain of the amplifier. =Differential gain
• Used to null out noise or bias-voltages that appear at both inputs, a low common-mode gain is usually desired.
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Differential and Common Gain
•
• Differential Gain (Ad):
• Ad = 1/2[R3/(R1+R3)] [(R4 + R2)/R2 + R4/R2]
• Mode Gain (Acm=VOUT/ Vcm)
• Acm = [R3/(R1+R3)] [(R4 + R2)/R2 - R4/R2]
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Charge amplifier• Constructed using op-amps with a
feedback capacitor.• The charge amplifier just transfers
the input charge to another reference capacitor and produces an output voltage equal to the voltage across the reference capacitor
• The circuit acts as a charge-to-voltage converter.
• The input impedance of the circuit is almost zero
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Capacitance Multiplier
• Uses an amplifier to make a capacitor function like a capacitor that is much large.
• Used as a capacitance multiplier in such a way that multiple small physical capacitances are combined in the integrated circuit technology to yield a large overall capacitance.
• The aim is often to multiply the original capacitance value hundreds and thousands of times.
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Oscillators
• Produces a repetitive, oscillating electronic signal, often a sine wave or a square wave.
• convert direct current (DC) from a power supply to an alternating current signal.
• It contains an energy-storing element (a capacitor or, more rarely, an inductor)
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Active FILTERS
• Types:
• Low pass filter
• High pass filter
• Band pass filter
• Band reject filter
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Active Filters• A filter contains a device like an Op Amp
• LP allow low frequencies HP allow high frequencies
• Cut of frequency :a cutoff frequency is a frequency level
above or below where a device fails to operate.
R2
+
-
+
V0
__
+ Vcc
- Vcc
-
+
R1
C
Low pass filter
Low pass filter transfer
function
Low pass filter Cutoff
frequency
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Low Pass Filter
• Passes low frequency signals with amplification and gain control
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Active Low Pass Filter with Amplification• the amplitude of the output is increased by the pass band
gain, AF of the amplifier.
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Frequency Response Curve
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High Pass Filter
• Passes high frequency signals with amplification and gain control
First Order Active High Pass Filter with 1 Gain
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Active Band Pass Filter
• Frequency selective filter circuit
• Range is set between two cut-off frequency points “lower frequency” ( ƒL ) and the “higher frequency” ( ƒH ) while attenuating any signals outside of these two points.
• Made by cascading together a single Low Pass Filter with a single High Pass Filter .
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Active Band Pass Filter Circuit
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Band reject filter
• Band stop filters reject a specified band of
• frequencies and pass all others.
• The response is opposite to that of a bandpass
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Graphical representation
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