james kelly nathan knight gustavo lee n.
Download
Skip this Video
Loading SlideShow in 5 Seconds..
Operational Amplifiers PowerPoint Presentation
Download Presentation
Operational Amplifiers

Loading in 2 Seconds...

play fullscreen
1 / 32

Operational Amplifiers - PowerPoint PPT Presentation


  • 98 Views
  • Uploaded on

James Kelly Nathan Knight Gustavo Lee. Operational Amplifiers. Presentation Outline. Introduction Characteristics of Ideal and Real Op-Amps Basic Circuits of Op-Amps Applications Exercise. What is an Op-Amp?.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about 'Operational Amplifiers' - livia


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
james kelly nathan knight gustavo lee
James Kelly

Nathan Knight

Gustavo Lee

Operational Amplifiers

presentation outline
Presentation Outline
  • Introduction
  • Characteristics of Ideal and Real Op-Amps
  • Basic Circuits of Op-Amps
  • Applications
  • Exercise
what is an op amp
What is an Op-Amp?
  • An Operational Amplifier (known as an “Op-Amp”) is an integrated circuit that sets an output voltage based on the input voltages provided.
  • In a circuit, it is used to perform an operation and an amplification where the operation may be add, subtract, filter, integrate, differentiate, etc.
  • Op-Amps are composed of transistors, resistors, capacitors, and diodes.
brief history
Brief History
  • 1941: Karl Swartzel of Bell Labs developed the first Op-Amp.
    • Used 3 vacuum tubes, only one input (inverting), and operated on +350 V to achieve 90 dB gain.
  • 1947: Loebe Julie developed the Op-Amp as it is known today, with two inputs – inverting and non-inverting.
    • The differential input made a whole range of new functionality possible.
  • 1953: First commercially available Op-Amp.
    • George A. Philbrick Researches (GAP-R). GAP-R pioneered the first reasonable-cost, mass-produced operational amplifier
  • 1961: Advent of solid-state, discrete Op-Amps.
    • Made possible by the invention of the silicon transistor, which led to the concept of Integrated Circuits (IC)
    • Reduced power input to ±15V to ±10V
  • 1962: Op-Amp in a potted module.
    • Packaging in small black boxes allowed for integration with a circuit
brief history1
Brief History
  • 1963: First monolithic IC Op-Amp, the μA702, designed by Bob Widlar at Fairchild Semiconductor.
    • Monolithic ICs consist of a single chip
  • 1968: Release of the μA741
    • The μA741 became the canonical Op-Amp, from which many modern op-amps base their pinout from, and is still in production today.
presentation outline1
Presentation Outline
  • Introduction
  • Characteristics of Ideal and Real Op-Amps
  • Basic Circuits of Op-Amps
  • Applications
  • Exercise
basic op amp open loop
Basic Op-Amp (Open-Loop)
  • : positive power supply
  • : negative power supply
  • : non-inverting input terminal
  • : inverting input terminal
  • : output terminal
    • ,,are all referenced to ground
ideal op amp
Ideal Op-Amp
  • Temperature-independent.
  • The maximum output voltage value is the supply voltage (saturation):
  • What this means:
    • Current flow into the op-amp from either input terminal is zero.
    • Differential voltage between the two input terminals is zero.
real op amp
Real Op-Amp
  • Operating temperature range:
    • Commercial:
    • Industrial:
    • Military:
saturation
Saturation

Vout

  • Saturation results when the output voltage is equal to the power supply’s voltage
  • In typical op-amps, the saturation level is about 80% of the supply voltage.
  • Positive Saturation Cutoff:
  • Linear Mode:
  • Negative Saturation Cutoff:

Vsat+

Slope = G

Vin

Vsat-

Saturation

Cutoff Points

presentation outline2
Presentation Outline
  • Introduction
  • Characteristics of Ideal and Real Op-Amps
  • Basic Circuits of Op-Amps
  • Applications
  • Exercise
open loop vs closed loop
Open Loop vs. Closed Loop
  • A closed-loop op-amp has feedback from the output back to one of the inputs, whereas an open-loop op-amp does not.

Open-Loop

Closed-Loop

negative vs positive feedback
Negative vs. Positive Feedback
  • Negative feedback connects the output to the inverting input (-), whereas positive feedback connects the output to the non-inverting input (+).

Negative Feedback

Positive Feedback

negative vs positive output
Negative vs. Positive: Output
  • Negative feedback op-amps can produce any voltage in the supply power range.
  • Positive feedback op-amps can only produce the maximum and minimum voltages of the range.

Vout

Vout

Vsat+

Vsat+

Vin

Vin

Vsat-

Vsat-

Negative Feedback

Positive Feedback

inverting op amp
Inverting Op-Amp
  • Functionality: to amplify the input voltage to output voltage with a negative gain.
non inverting op amp
Non-Inverting Op-Amp
  • Functionality: to amplify the input voltage to output voltage with a positive gain.
integrating op amp
Integrating Op-Amp
  • Functionality: takes the summation of input voltages over time and provides that as the output signal
  • =
derivative op amp
Derivative Op-Amp
  • Functionality: takes the rate of change of the inverted input voltage signal and provides that as the output signal
differential op amp
Differential Op-Amp
  • Functionality: takes the difference between two signals and provides that as the output
  • If :
  • Moreover, if :
summing op amp
Summing Op-Amp
  • Functionality: takes the sum of two or more input voltages and provides an output voltage proportional to the negative of the algebraic sum
  • If :
  • Moreover, if :
  • By setting , the summing op-amp can be used as an averaging operator:
presentation outline3
Presentation Outline
  • Introduction
  • Characteristics of Ideal and Real Op-Amps
  • Basic Circuits of Op-Amps
  • Applications
  • Exercise
applications
Applications
  • Active filters
    • Signal processing
    • Digital Image processing
  • Strain gauges
  • Control circuits
    • PID controllers for aircraft
    • PI controllers for temperature measurement circuitry
  • And much more…
low pass filter high pass filter
Low-Pass Filter High-Pass Filter
  • Attenuates frequencies below the cutoff frequency.
  • Cutoff frequency (Hz):
  • Gain in the passband:
  • Attenuates frequencies above the cutoff frequency.
  • Cutoff frequency (Hz):
  • Gain in the passband:
strain gauge
Strain Gauge
  • Strain gauges consist of a pattern of resistive foil mounted on a backing material.
  • As the foil is subjected to stress, the resistance of the foil changes in a defined way.
  • This results in an output signal directly related to the stress value, typically a few millivolts.
  • Op-Amps are utilized to amplify the output signal level to 5~10 V, a suitable level for application to data collection systems.
pid controller
PID Controller
  • A proportional-integral-derivative (PID) controller is a generic feedback mechanism widely used in industrial control systems.
    • It calculates an “error” value as the difference between a measured process variable and a desired setpoint.
    • Using this error, it calculates a control input using tuning parameters ,,and to drive the error to zero.
pid controller1
PID Controller
  • So where do op-amps come in?
    • The error is calculated using a Summing Op-Amp.
    • Using this error voltage:
      • The derivative of the error is calculated using a Derivative Op-Amp.
      • The integral of the error is calculated using an Inverting Op-Amp.
    • The tuning parameters , , and can be selected by appropriate selection of resistors and capacitors.
and much more
And much more…
  • Comparators
  • Detectors
    • Threshold detector
    • Zero-level detector
  • Oscillators
    • Wien bridge oscillator
    • Relaxation oscillator
  • Level shifters
presentation outline4
Presentation Outline
  • Introduction
  • Characteristics of Ideal and Real Op-Amps
  • Basic Circuits of Op-Amps
  • Applications
  • Exercise
exercise
Exercise
  • Consider the circuit above running for 5 seconds. Find when:
    • , , ,
references
References
  • Cetinkunt, Sabri. Mechatronics. Hoboken, NJ: John Wiley & Sons Inc., 2007.
  • Jung, Walter G. Op Amp Applications Handbook. Analog Devices, Inc., 2005.
  • “Operational Amplifier.” http://en.wikipedia.org/wiki/Operational_amplifier.
  • “Operational Amplifier Applications.” http://en.wikipedia.org/wiki/Operational_amplifier_applications.
  • “The Strain Gauge.” http://web.deu.edu.tr/mechatronics/TUR/strain_gauge.htm.
  • “The PID Controller.” http://en.wikipedia.org/wiki/PID_controller.
  • “Feedback in Electronic Circuits: An Introduction.” http://ecee.colorado.edu/~ecen4827/lectures/dm_feedback1.pdf.
  • “Differentiator and Integrator Circuits” http://www.allaboutcircuits.com/vol_3/chpt_8/11.html.
  • “Inverting Op-Amp” http://www.wiringdiagrams21.com/2009/12/17/basic-inverting-op-amp-circuit-diagram/
the end
The End
  • Questions?