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Information about Instrumentation Amplifier

You may be looking for instrument amplifier, as used for amplifying musical instruments. This page is about the electronic device.


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Typical instrumentation amplifier schematic


An instrumentation amplifier is a type of differential amplifier that has been specifically designed to have characteristics suitable for use in measurement and test equipment. These characteristics include very low DC offset, low drift, low noise, very high open-loop gain, very high common-mode rejection ratio, and very high input impedances. They are used where great accuracy and stability of the circuit both short- and long-term are required.

The most commonly used instrumentation amplifier circuit is shown in the figure. The gain of the circuit is



The ideal common-mode gain of an instrumentation amplifier is zero. In the circuit shown, common-mode gain is caused by mismatches in the values of the equally-numbered resistors and by the non-zero common mode gains of the two input op-amps. Obtaining very closely matched resistors is a significant difficulty in fabricating these circuits, as is optimizing the common mode performance of the input op-amps. See - Smither, Pugh and Woolard: ‘CMRR Analysis of the 3-op-amp instrumentation amplifier', Electronics letters, 2nd February 1989.

Instrumentation amplifiers can be built with individual op-amps and precision resistors, but are also available in integrated circuit form from several manufacturers (including Texas Instruments, Analog Devices, Linear Technology and Maxim Integrated Products). An IC instrumentation amplifier typically contains closely matched laser-trimmed resistors, and therefore offers excellent common-mode rejection.

See also

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instrument amplifier is an electronic amplifier designed for use with an electric or electronic musical instrument, such as an electric guitar, an electric bass, or an electric keyboard.
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differential amplifier is a type of electronic amplifier that multiplies the difference between two inputs by some constant factor (the differential gain). A differential amplifier is the input stage of operational amplifiers, or op-amps, and emitter coupled logic gates.
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Direct current (DC or "continuous current") is the constant flow of electric charge. This is typically in a conductor such as a wire, but can also be through semiconductors, insulators, or even through a vacuum as in electron or ion beams.
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Drift may refer to:

The effect of wind and water pushing a body (person or thing around) usually in a current. A difference in drift rates becomes an urgent matter in a Man Over Board Event, and a positional drift
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In science, and especially in physics and telecommunication, noise is fluctuations in and the addition of external factors to the stream of target information (signal) being received at a detector.
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The open-loop gain of an operational amplifier is the gain obtained when no feedback is used in the circuit. Open loop gain is usually exceedingly high; in fact, an ideal operational amplifier has infinite open-loop gain. Typically an op-amp may have an open-loop gain of around .
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The common-mode rejection ratio (CMRR) of a differential amplifier (or other device) measures the tendency of the device to reject input signals common to both input leads.
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The input impedance, load impedance, or external impedance of a circuit or electronic device is the Thévenin equivalent impedance looking into its input.
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accuracy is the degree of conformity of a measured or calculated quantity to its actual (true) value. Accuracy is closely related to precision, also called reproducibility or repeatability, the degree to which further measurements or calculations show the same or similar
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Stability can refer to:
  • Aircraft flight Stability (aircraft)
  • Atmospheric stability, a measure of the turbulence in the ambient atmosphere
  • BIBO stability (Bounded Input, Bounded Output stability), in signal processing and control theory, part of electrical

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electrical network is an interconnection of electrical elements such as resistors, inductors, capacitors, transmission lines, voltage sources, current sources, and switches.
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resistor is a two-terminal electrical or electronic component that resists an electric current by producing a voltage drop between its terminals in accordance with Ohm's law: The electrical resistance
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integrated circuit (also known as IC, microcircuit, microchip, silicon chip, or chip) is a miniaturized electronic circuit (consisting mainly of semiconductor devices, as well as passive components) that has been manufactured in the surface of a
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Texas Instruments

Public (NYSE:  TXN )
Founded 1930 (as GSI), 1951 (as TI)[1]
Headquarters Dallas, Texas, USA

Key people Tom Engibous, Chairman
Rich Templeton, President & CEO
Kevin March, CFO
Brian Bonner, CIO
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Analog Devices

Public (NYSE:  ADI )
Founded Cambridge, Massachusetts (1965)
Headquarters Norwood, Massachusetts

Key people Jerald G Fishman,
CEO & President,
Ray Stata,
Chairman of the Board
Industry Semiconductors
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Founded in 1981, Linear Technology Corporation is a supplier of high performance analog integrated circuits.

Product Line

Linear Technology Corporation designs, manufactures and markets a broad line of standard high performance integrated circuits.
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Maxim Integrated Products Pink Sheets: MXIM , commonly known as "Maxim," is a semiconductor company that designs and manufactures analog and mixed-signal integrated circuits. It was founded in 1983 and has headquarters in Sunnyvale, California, United States.
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This article has been tagged since August 2007.
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operational amplifier, usually referred to as an op-amp for brevity, is a DC-coupled high-gain electronic voltage amplifier with Differential Inputs and, usually, a single output.
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This article illustrates some typical applications of solid-state integrated circuit operational amplifiers. A simplified schematic notation is used, and the reader is reminded that many details such as device selection and power supply connections are not shown.
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