What is Operational amplifiers: Definition and 17 Discussions

An operational amplifier (often op amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. In this configuration, an op amp produces an output potential (relative to circuit ground) that is typically 100,000 times larger than the potential difference between its input terminals. Operational amplifiers had their origins in analog computers, where they were used to perform mathematical operations in linear, non-linear, and frequency-dependent circuits.
The popularity of the op amp as a building block in analog circuits is due to its versatility. By using negative feedback, the characteristics of an op-amp circuit, its gain, input and output impedance, bandwidth etc. are determined by external components and have little dependence on temperature coefficients or engineering tolerance in the op amp itself.
Op amps are used widely in electronic devices today, including a vast array of consumer, industrial, and scientific devices. Many standard IC op amps cost only a few cents; however, some integrated or hybrid operational amplifiers with special performance specifications may cost over US$100 in small quantities. Op amps may be packaged as components or used as elements of more complex integrated circuits.
The op amp is one type of differential amplifier. Other types of differential amplifier include the fully differential amplifier (similar to the op amp, but with two outputs), the instrumentation amplifier (usually built from three op amps), the isolation amplifier (similar to the instrumentation amplifier, but with tolerance to common-mode voltages that would destroy an ordinary op amp), and negative-feedback amplifier (usually built from one or more op amps and a resistive feedback network).

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  1. PRITAM the cat of Ne

    Engineering Op-Amp circuit output analysis trouble

    THE ANSWER IS GIVEN: 6V, but according to me as the positive terminal is grounded the negative terminal will be virtually grounded (0V), from ohm's law (applying to the two series resistance) it is expected that Vo is 0V! I don't know where I am getting wrong!
  2. Jason-Li

    Operational Amplifiers & Resistors to form a Black Box

    So basically I am trying to give an output of Vo = 10(V2-V1) From Figure 9 Example Gain of first Op Amp = Rf / R1, if R1 & R2 are equal. What's throwing me off is using 5 resistors to create a circuit rather than 6 or just 3. My initial thoughts were the following: To use the first loop...
  3. HansBu

    Solving Diff. Eqn & Designing Circuits: An Understanding

    where: 𝑣𝑖𝑛(𝑡)=0.3𝑐𝑜𝑠100𝑡 I have read all over the internet that this differential equation can be solved by isolating the term with the highest degree on one side of the equation. After doing so, I integrated it. However after integrating, I don't know that the next step is. Can anyone help me...
  4. R

    Sawtooth wave generator from operational amplifiers

    Homework Statement Homework Equations See above in the question The Attempt at a Solution I know that I need to be using a summing amp with the sinusoidal terms but I am struggling to calculate the input values that I need, also I think I need a capacitor in place of R6 but I'm not...
  5. akaliuseheal

    Hysteresis of a voltage comparator

    Hello, I am designing a circuit which basically takes two voltages (V1,V2) and based upon which one of the two is greater, turns corresponding LED. So, I have got to the part where I have output from differential op amp that is the input of the inverting voltage comparator with hysteresis...
  6. J

    Operational Amplifiers Homework Help: Get 20V Output in 2 Hours

    Homework Statement http://prntscr.com/kjbhim Okay, so I need to draw an op-amp circuit that'll give a 20V output but I have no idea how to start this and this is due in two hours. Could someone please point out to me how to start this off? Thank you so much. Homework EquationsThe Attempt at...
  7. A

    What are the values of Rf and V2 for the given circuit?

    Homework Statement Hello, I am trying to Calculate The Resistance Rf and the value of the Voltage V2. The setup is a logarithmic Op amp connected to a differential Op amp. Both Op amps obey the Golden Rules. Attached below is my attempt at the solution and the question. Currently, I have an...
  8. K

    Opamp for MF/RF ranges (1.0-1.2MHz)

    Hello! I have a bit of trouble finding general op-amps that can amplify at medium frequency ranges, and with a good enough gain of 200 or 46dB. My max desired operating frequency is around 1.2MHz so I don't really care if it no longer amplifies much at frequencies higher than this. I am aware...
  9. H

    Op Amp Basics: Why Does It Not Input Current?

    Ah, the op amp... so easy to learn. Yet i have a question: Why the op amp does not input any current? Is it made by some sort of CMOS technology?
  10. EngrHdr

    Dual Supply Summing Amplifier

    Hi everyone, I am trying to make a Summing Amlifier. I have simulated on computer where it is working correctly, but on real circuit it is showing some mal functioning. I am using OP 27 Op Apmp. The circuit diagram is attached. When I try to add DC voltage to AC sine wave, initially sine wave...
  11. E

    Quick question about operational amplifiers

    Homework Statement Does a noninverting operational amplifier amplify the frequency of an input, ex. a 2 kHz square wave of amplitude 100mV peak-peak, or just the voltage?
  12. P

    Operational Amplifiers - Saturation

    I am an A level physics student. I have a doubt regarding the saturation of op-amps. For a circuit with a dual power supply, each supply has an emf VS. My doubt is, why is the MAXIMUM magnitude of the output voltage VS? Shouldn't it be VS - (- VS) = 2VS? (Since the potential difference is the...
  13. G

    Electrical Engineering - Operational Amplifiers

    Hi in a homework problem I'm trying to solve circuit. I'm getting the output current of an operational amplifier going into the operational amplifier. Is this allowed? If not than I'm violating Kirchhoff Current law and my other calculated values of the circuit must be wrong. Thanks for...
  14. ElijahRockers

    Solve Op Amp Saturation: Find Rf & Output Current

    Homework Statement Va = 4V Vb = 9V Vc = 13V Vd = 8V The 220k resistor is replaced by a variable resistor Rf. What value of Rf will cause the Op Amp to saturate? Note: 0 ≤ Rf ≤ ∞ When Rf obtains that value, what will be the current flowing into the output terminal of the op amp? The...
  15. E

    Characteristics of Ideal Operational Amplifiers

    One of the characteristics of an ideal op amp is that it have infinite input impedance/resistance. Now, I want you to tell me if I am correct : The voltage source is likely to have some internal resistance. By having an infinite input resistance, no current is drawn from the voltage...
  16. E

    Operational Amplifiers Homework: Solving for Voltage & Current

    Homework Statement http://desmond.imageshack.us/Himg853/scaled.php?server=853&filename=opamp.jpg&res=medium relevant equations v=ir (ohm's law) kirchoff's current law The Attempt at a Solution i'm concerned about the bottom left node in this picture. current into an ideal op amp is zero...
  17. Femme_physics

    Trying to understand how operational amplifiers work

    So I'm looking at this non-inverting Op-Amp http://img140.imageshack.us/img140/6660/shomermofa.jpg Trying to understand how Op-Amps work. It seems rather strange they're saying no current flows from + to - because then how does the current from Vin spreads through? After all, there...