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Topic: Operational amplifier


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In the News (Tue 16 Jul 19)

  
 Operational amplifier apparatus - Patent 5777515
According to the present invention, an operational amplifier apparatus for outputting to an output terminal a voltage corresponding to a difference between a voltage in a first input terminal and a voltage in a second input terminal is provided.
An operational amplifier apparatus according to claim 3, wherein a relationship W1/L1>W2/L2 (where a channel width and a channel length of the first transistor are denoted by W1 and L1, respectively, and a channel width and a channel length of the second transistor are denoted by W2 and L2, respectively) is satisfied.
An operational amplifier apparatus according to claim 3, wherein the current supply section comprises a transistor, a control terminal and one of terminals other than the control terminal of which are connected to one of the terminals other than the control terminal of the second transistors.
www.freepatentsonline.com /5777515.html   (5443 words)

  
 High-speed low-drift operational amplifier - Patent 4293819
In the above-mentioned circuit arrangement, the inverting input terminal of the wide-band operational amplifier and the non-inverting input terminal of the low frequency operational amplifier correspond respectively to the inverting and non-inverting input terminals of a high-speed low-drift operational amplifier according to the present invention.
However, since the output impedance of the low-frequency operational amplifier 14 becomes large in a high frequency region, the step response of the wide-band operational amplifier 13 is deteriorated, and thus the wide-band characteristic is degraded.
When the cut-off frequencies of the wide-band operational amplifier 13, the low-frequency operational amplifier 14 and the coefficient circuit (made up of the operational amplifier 14, the resistor R.sub.2 and the capacitor C.sub.1) are given by f.sub.cl, f.sub.c2 and f.sub.1, respectively, oscillation of the circuit shown in FIG.
www.freepatentsonline.com /4293819.html   (1917 words)

  
 Operational amplifier
This open-loop operation is practical only when the operational amplifier is used as a comparator (a circuit which compares two input signals or compares an input signal to some fixed level of voltage).
Operational amplifiers are used with degenerative (or negative) feedback which reduces the gain of the operational amplifier but greatly increases the stability of the circuit.
The operational amplifier is represented by the triangle-like symbol while the operational circuit includes the resistors and any other components as well as the operational amplifier.
www.tpub.com /neets/book8/32d.htm   (734 words)

  
 Fundamental and applications of operational amplifier
The Operational Amplifier is a differential amplifier having a large voltage gain, very high input impedance and low output impedance.
The operational amplifier is connected using two resistors RA and RB such that the input signal is applied in series with RA and the output is connected back to the inverting input through RB.
A high impedance signal source will suffer loading effects when connected to such amplifier and therefore it is sometimes necessary to isolate the signal source by connecting it to a voltage follower to the next stage.
www.electronics-project-design.com /Operational_Amplifier.html   (651 words)

  
 Operational amplifier - Wikipedia, the free encyclopedia
This is the basis of the analog computer where op-amps were used to model the basic mathematical operations (addition, subtraction, integration, differentiation, and so on).
However, an ideal operational amplifier is an extremely versatile circuit element, with a great many applications beyond mathematical operations.
Slewing is usually caused by internal capacitances in the amplifier, especially those used to implement its frequency compensation.
en.wikipedia.org /wiki/Operational_amplifier   (3138 words)

  
 OPERATIONAL AMPLIFIER   (Site not responding. Last check: 2007-11-05)
An operational amplifier (op-amp) is a device with two inputs and a single output.
While the output node of the whole amplifier circuit may be the output node of the op-amp, the input to the amplifier circuit will not be, in general, a voltage applied across the input terminals of the op-amp.
In such a case, one could either use theoutput of the inverting amplifier as the input to a second inverting amplifier which would cause the total voltage gain to be positive.
www.bergen.org /EST/Backup/electronic_projects/amplifier.htm   (1195 words)

  
 741 Op-Amp Tutorial, op-amps, Operational Amplifier
The term "operational amplifier" goes all the way back to about 1943 where this name was mentioned in a paper written by John R. Ragazzinni with the title "Analysis of Problems in Dynamics" and also covered the work of technical aid George A. Philbrick.
Supply-voltage operating range for the 741 is -4.5 volts (minimum) to -18 volts (max), and it is specified for operation between -5 and -15 Vdc.
Supply-voltage operating range for the 741 is +4.5 volts (minimum) to +18 volts (maximum), and it is specified for operation between +5 and +15 Vdc.
www.uoguelph.ca /~antoon/gadgets/741/741.html   (4734 words)

  
 Operational Amplifiers
Operational amplifiers can be used to perform mathematical operations on voltage signals such as inversion, addition, subtraction, integration, differentiation, and multiplication by a constant.
The operational amplifier amplifies the difference between the non-inverting input and the inverting input.
Since the difference between the operational amplifier input voltages are practially zero and the internal input resistance is very large, we can make the assumption that the current flowing into the amplifier through either of the input terminals is so small as to be negligible.
www.facstaff.bucknell.edu /mastascu/eLessonsHTML/OpAmps/OpAmp2.html   (4197 words)

  
 OPERATIONAL AMPLIFIER BASICS by Harry Lythall
To modify the circuit to operate from a single supply, we have to move the amplifier DC operating point away from 0v to something else.
The AF amplifiers discussed so-far have the input signal fed into the + input which means that the output signal is in the same phase as the input signal.
If we needed an amplifier to have a gain of 190 then we would be far better off to have two cascaded amplifier; each with a voltage gain of just 14.
web.telia.com /~u85920178/begin/opamp00.htm   (4628 words)

  
 OPERATIONAL AMPLIFIER
An operational amplifier or popularly known as Op-Amp, is a solid state IC with transistors that uses external feedback to control its functions.
The main types are: inverting amplifier, non-inverting amplifier, voltage follower, difference amplifier, summing amplifier, integrator, differentiator, comparator, instrumentation amplifier, Schmitt trigger, inductance gyrator.
Other uses are in differential amplifiers, differentiators and integrators, filters, precision rectifiers, voltage and current regulators, analogue calculators, analogue-to-digital converters, digital-to-analog converters, and ultrasonic distance measurement.
www.partminer.com /glossaryhtml/operational_amplifier.htm   (239 words)

  
 Lessons In Electric Circuits -- Volume III (Semiconductors) - Chapter 8   (Site not responding. Last check: 2007-11-05)
The amplifier is still being supplied with 30 volts overall, but with the split voltage DC power supply, the output voltage across the load resistor can now swing from a theoretical maximum of +15 volts to -15 volts, instead of +30 volts to 0 volts.
That triode amplifies and inverts the output of the differential pair for a larger voltage gain, then the amplified signal is coupled to the second triode of the same dual-triode tube in a noninverting amplifier configuration for a larger current gain.
As it was in the vacuum tube circuit, the purpose of a differential pair is to amplify and convert a differential voltage between the two input terminals to a single-ended output voltage.
www.ibiblio.org /obp/electricCircuits/Semi/SEMI_8.html   (14506 words)

  
 Operational Amplifier
A circuit using an operational amplifier as an inverting amplifier will be constructed.
An operational amplifier is a very high gain amplifier which commonly comes in three packages - the 8-lead mini-DIP (dual in-line package, used in the laboratory), standard 16-lead DIP and the TO-99 metal can.
This can be done by measuring the current supplied to the operational amplifier by the positive lead of the power supply.
www.chembio.niu.edu /Electrochem/lab1.htm   (329 words)

  
 Application of the Operational Transconductance Amplifier (OTA)   (Site not responding. Last check: 2007-11-05)
The application of the operational transconductance amplifier (OTA) in the design of simple amplifiers with voltage-controllable gain and to the design of firs-order and second-order active filters with controllable gains and controllable critical frequencies is demonstrated.
This paper demonstrates the usefulness of the operational transconductance amplifier (OTA) as a replacement for the conventional op-amp in both first and second-order active filters.
It is at least partially intended to acquaint the technology student w ith the rudiments of operation of the OTA, as well as the practicalities of using the presently available commercial OTA’s.
et.nmsu.edu /~etti/winter98/electronics/grise/wrg.html   (2031 words)

  
 Differential operational transconductance amplifier (US5936466)
The OTA includes a pair of input inverters for receiving differential input signals, a common-mode voltage control circuit for controlling the DC voltage levels of the inverters, and a Q-control circuit for adjusting the OTA's output conductance.
The high-gain amplifier has a pair of comparators for respectively comparing the DC voltage levels of the inverter outputs with a reference voltage.
A differential operational transconductance amplifier (OTA) for amplifying a differential input having positive and negative input signals, the OTA having positive and negative outputs and an output conductance, comprising:
www.delphion.com /details?pn10=US05936466   (355 words)

  
 [No title]
The op-amp is basically a differential amplifier having a large voltage gain, very high input impedance and low output impedance.
The non-inverting input (pin 3) to the op-amp is biased at 50% of the supply voltage (4.5 volts) by a couple 1K resistors connected across the supply.
Since both inputs will be equal when the op-amp is operating within it's linear range, the voltage at the inverting input (pin 2) and the emitter of the buffer transistor (2N3053) will also be 4.5 volts.
ourworld.compuserve.com /homepages/Bill_Bowden/opamp.htm   (1349 words)

  
 Operational amplifier applications - Wikipedia, the free encyclopedia
Used as a buffer amplifier, to eliminate loading effects or to interface impedances (connecting a device with a high source impedance to a device with a low input impedance)
Is made by adding a non-inverting buffer to each input of the differential amplifier to increase the input impedance.
If the operational amplifier is considered ideal, the negative pin is virtually grounded, so the current flowing into the resistor from the source (and thus through the diode to the output, since the op-amp inputs draw no current) is:
en.wikipedia.org /wiki/Operational_amplifier_applications   (747 words)

  
 Operational Amplifier Circuits
They are called ``operational'' amplifiers, because they can be used to perform arithmetic operations (addition, subtraction, multiplication) with signals.
A circuit model of an operational amplifier is shown in Figure 22.
The output ranges of the amplifiers we built as part of Lab 3 were similarly limited by the supply voltage.
webpages.ursinus.edu /lriley/ref/circuits/node5.html   (998 words)

  
 An Operational Amplifier for a CMOS VLSI Design
This device is commonly used to amplify small signals, to add/subtract voltages, and in active filtering.
The "garden-variety" operational amplifier circuit shown at left was used as a basis for this design.
In a nutshell, an ac circuit analysis is performed on the differential amplifier using the appropriate small signal models for the transistors [2].
www.mathcad.com /Library/LibraryContent/MathML/opamp.htm   (1144 words)

  
 Useful Operational Amplifier Circuits
Operational amplifiers are useful devices that can be used for numerous types of operations on signals.
In this lesson you will examine a number of operational amplifier circuits that are useful in many situations.
, appears at the output of an operational amplifier that can often deliver more current without lowering the output voltage because the internal resistance of the operational amplifier is lower than the internal resistance of the original source.
www.facstaff.bucknell.edu /mastascu/eLessonsHTML/OpAmps/OpAmp3.html   (572 words)

  
 App Note Abstract: Understanding Operational Amplifier Specifications
Selecting the right operational amplifier for a specific application requires you to have your design goals clearly in mind along with a firm understanding of what the published specifications mean.
First, introductory topics on the basic principles of amplifiers are presented, including the ideal op amp model.
Second, a simplified circuit of an operational amplifier is discussed to show how parameters arise that limit the ideal functioning of the operational amplifier.
www.ti.com /sc/docs/psheets/abstract/apps/sloa011.htm   (134 words)

  
 Operational Amplifiers   (Site not responding. Last check: 2007-11-05)
The operational amplifier (op-amp) was designed to perform mathematical operations.
The push-pull amplifier transmits a large current to the load and hence has a small output impedance.
Cheap IC versions of operational amplifiers are readily available, making their use popular in any analog circuit.
www.phys.ualberta.ca /~gingrich/phys395/notes/node99.html   (235 words)

  
 (WO/1993/001863) MEDICAL STIMULATOR WITH OPERATIONAL AMPLIFIER OUTPUT CIRCUIT   (Site not responding. Last check: 2007-11-05)
A first input (22) to the operational amplifier is coupled through a virtual load (104) to a probe electrode in close proximity to the body tissue.
A defined voltage signal may be provided to the second input to the amplifier, and the amplifier correspondingly delivers current through the virtual load (104) to the probe electrode as the amplifier maintains equal voltage levels at its two inputs.
After termination of the defined voltage signal, the amplifier functions to restore the electrode-tissue system to its previous electrical equilibrium condition and to sense induced or spontaneous electrical activity in the tissue.
www.wipo.int /pctdb/en/wo.jsp?WO=1993/01863   (497 words)

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