Electronics Circuit Design Presentation on OP AMP APllications

1. ECD II Presentation
OP-AMP Applications

2. • Presented by Group 12
• Aroosa
• Sheher
• Sidra Ali

3. 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

4. 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 looks
like to a lay-person

5. What is an Op-Amp? – The
Surface
• What an Op-Amp looks
• .
like to an engineer

6. 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

7. 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

8. 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)

9. Ideal Op-Amp Characteristics

10. Types of Op-Amps
o Inverting
oNon-inverting
oSumming amplifier
oThe voltage follower
o Integrator
oDifferentiator

11. Applications of Op-Amps
• Comparator
• Integration and differentiation
• Charge amplifier
• Capacitance multiplier
• Oscillators
• Filters
• Audio and video preamplifiers and buffers

12. Applications of Op-Amps
• Voltage regulator and current regulator
• Digital-to-analog converter
• Voltage clamps
• Oscillators and waveform generators
• Analog computer

13. 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.

14. Integration
•Performs the mathematical
operation 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.

15. 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.

16. 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]

17. 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

18. 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.

19. 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)

20. Active FILTERS
• Types:
• Low pass filter
• High pass filter
• Band pass filter
• Band reject filter

21. 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 

22. Low Pass Filter
• Passes low frequency signals with amplification and gain
control

23. Active Low Pass Filter with
Amplification
• the amplitude of the output is increased by the pass band
gain, AF of the amplifier.

24. Frequency Response Curve

25. High Pass Filter
• Passes high frequency signals with amplification and gain control
First Order Active High Pass Filter with 1 Gain

26. 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 .

27. Active Band Pass Filter Circuit

28. 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

29. Graphical representation