Electrical Engineering Stack Exchange
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Questions tagged [instrumentation-amplifier]

An instrumentation amplifier (InAmp) is an integrated circuit or operational amplifier topology that has high input impedance differential inputs and a low impedance single-sided output. Because of precision laser-trimming techniques for passive circuit elements, InAmps implemented as integrated circuits can achieve impressive common mode rejection ratios, while discrete OpAmp implementations can be disappointing in this regard.

Recommended reading

A Designer's Guide to Instrumentation Amplifiers, written at Analog Devices Inc. by Charles Kitchin and Lew Counts, gives a comprehensive overview of Instrumentation Amplifier technology and application. This classic text is available free of charge.

Three-OpAmp Instrumentation Amplifiers: Advantages & Disadvantages

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Understanding the guarding circuit in an instrumentation amplifier

I've got a project to make but I have trouble understanding what is actually going on. In circuit below, I have to calculate the resistor values, choose op-amps and explain how the whole thing works. This is an in-amp for EMG and I can't understand…
Archimedes
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Instrumentation amplifier (weird layout)

I'm having a hard time figuring out how the following circuit works. I studied the theory behind instrumentation amplifiers and from what I learned they are used to measure a difference between two voltage inputs and amplify the signal. Now in the…
user5129251
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Why use a three op-amp instrumentation amplifier?

This TI application note shows this typical instrumentation amplifier (InAmp) with three op-amps (p.4): Further down the page the following two op-amp InAmp is shown: The former is more common (I think) and easier to understand, but is there a…
Federico Russo
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Is an instrumentation amplifier design same with a standard op amp?

Is instrumentation amplifier nothing but a standard op-amp with a different configuration? I wonder if the inner complicated circuit of an instrumentation amplifier same with standard op-amp's. At one forum I read: "An instrumentation amplifier is…
user16307
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What is the reference pin on an instrumentation amplifier used for?

Happy new year all! I'm wondering how to correctly use the reference pin on an INA128 Instrumentation Amplifier. Is there a way to use this pin to eliminate negative voltages (i.e. do a voltage shift)? Thanks again.
user1883691
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AD623-Unable to change gain or reference voltage

I have an air flow sensor (FS1012-1100NG) with expected differential output voltages ranging from -1mV to 20mV and I need to 1) know the precise value (mV) and gain to correlate V with airflow 2) make sure that value has long-term stability (order…
Lifespark
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Circuit of Instrumentation Amplifier

Please tell me what will happen if the instrumentation amplifier is constructed as this circuit? As in this, two resistances R1 are grounded in between? What is the problem in this circuit?
user170106
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Understanding common mode vs output voltage graph for instrumentation amps

What are limitations on the design imposed by this graph? Say, if I want my output to span 0V - 3.3V, does this mean that I should position my input signal at 2.5V? edit: InAmp in question is AD8226
miceuz
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Amplification of load cell signal with AD623 IC

I am trying to amplify the signal from a load cell using an AD623 instrumentation amplifier. (source: instructables.com) Please refer to https://www.instructables.com/answers/Amplifying-load-cell-signal-with-AD623-problem/ for the schematic. The…
Chris
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Op-amp output wanders over the course of a few seconds

In one of our designs we are doing signal conditioning of a load cell (Wheatstone bridge) We have an issue where the main instrumentation amplifier an AD8224 has an output signal that wanders by around 20mV over the course of 10's of seconds. We…
Hugoagogo
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Rectification of Micro DC voltage levels?

I am building a payload for a high-altitude Balloon launch in the club I started which will be measuring DC voltages (electric field) at different altitudes using a wire dipole or two metal plate formation. I obviously need a low noise amplifier to…
skyler
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Problem with AD8230

I want to use the AD8230 instrumentation amplifier. I have bought one and connected it like this: The datasheet says that this will be gain of 2, so on the output (pin 8) I should have +1 V. Sadly, I have +2.8 V, even though I have increased the…
Felipe
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Instrumentattion amplifier gain appears to change

I made a very simple circuit to amplify a ~1 mV signal up to ~2 V. The input is a 0~2 mV DC signal from a scientific instrument. The problem: I made the circuit, and it worked as intended. The 1 mV signal became 0.2 V, with the intended gain of…
user4396936
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Subtract two voltages using two instrumentation amplifiers

I'm building a PI controller with inputs read using instrumentation amplifiers (for sensing resistors and floating grounds), rather than subtracting the two input signals with a third chip, is it possible to use the reference pin (as shown in the…
Enrique Mendez
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In-amp output clamps to reference voltage

I am using AD8231 instrumentation amplifier in unity gain configuration. I used the inbuilt op-amp to provide reference voltage as the datasheet suggests. A 4.4kHz sine wave generated with my professional signal generator (PC sound card) is fed into…
Ashton H.
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