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.
597 questions
-2 votes
1 answer
90 views
Butterworth Filter 2nd to 6th order [closed]
I found out using a 2nd order Butterworth filter at say 1khz can slice the frequency at both sides. Has anyone tried upgrading a 2nd order Butterworth to 6th order Butterworth in an existing circuit? ...
- 1,093
0 votes
0 answers
171 views
What could be source of these harmonics (248Hz, 496Hz, 744Hz, etc.)
This is the waveforms without harmonics: This is the waveforms with 248Hz harmonics present. Same settings in equipment and software. Any clue what could be causing the harmonics of 248Hz? See FFT of ...
- 1,093
0 votes
2 answers
215 views
How can I build an independent driven right leg (DRL) module?
https://www.biosemi.com/faq/cms&drl.htm The above is from a Biosemi bioamplfier I don't own. It has DRL. My g.USBamp bioamplifier (which I own) has no DRL and it can only accept +-250mV common ...
- 1,093
2 votes
5 answers
474 views
Driven right leg common mode suppression
(Image from https://www.mdpi.com/2076-3417/12/24/12897 ) I read a lot about driven right leg lately but there is some clarification I need to ask: Let's say the DRL amplifier feeds the inverse ...
- 1,093
3 votes
3 answers
198 views
How can electric field in body affect instrumentation amplifier?
(above from Metting van Rijn "High_quality recording of bioelectric events" Part 1) Edit: My question is if the person has capacitive coupling or electric field in the body, how does it ...
- 1,093
0 votes
2 answers
108 views
Unexpected LTSpice output in a three stage op-amp amplifier signal chain
I am currently designing a amplification signal chain (with 3 op-amps) for a signal that comes from a hydrophone with around 1nV amplitude and with a bandwidth of 10 to 100 kHz. For that I am using ...
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1 vote
1 answer
135 views
What if the ground in EEG/EMG has high impedance
What if the ground in EEG/EMG has high impedance to skin (say 40kOhm). Can it affect the signal. Since it is ground. It may not affect signal? This is one where the ground is used as reference. I ...
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1 vote
2 answers
159 views
Trouble utilizing intrumentation amplifier
I'm currently designing a signal conditioning circuit for a piezoelectric sensor, and am using an INA849 for the first stage of amplification. Currently, I'm only using a function generator and a ...
-2 votes
2 answers
100 views
What can shift up the noise floor FFT of an amplifier?
This is the FFT of the noise floor of an amplifier with low pass filer set at 1000Hz and high pass filter set at 100Hz. Why does the noise floor shift up overall? How can the amplifier do this and ...
- 1,093
4 votes
1 answer
266 views
How does the automatic switching function work on Nordic power profiler kit
I'm trying to understand the schematic of the Nordic power profiler kit. One part I don't understand is the automatic switch part. I even tried to use LTspice to simulate that part, but no luck. The ...
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0 votes
2 answers
89 views
INA317 Instrumentation amplifier with strain gauge strange behaviour
I have designed a PCB to read a strain gauge, in which I've used an INA317IDGKT instrumentation amplifier with a gain set to 200. The strain gauge i'm using is the ATO-LCC-DYMH-103 100kg, supplied ...
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1 vote
1 answer
93 views
Instrumentation Amplifier Circuit simulation not yielding expected results
I want to measure the voltage across a rheostat located in a remote and noisy environment. The rheostat is far from the main circuit, and its cable runs alongside many high-current-carrying cables. ...
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1 vote
2 answers
156 views
INA851 to amplify Wheatstone Bridge and transmit over 40m cable
I am looking to use the INA851 to amplify the differential signal from a Wheatstone bridge to a ±5V differential signal that will resist interference over a 40m shielded twisted-pair cable. It will be ...
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1 vote
1 answer
144 views
Relatively cheap thermocouple amplifier with only op-amps
I am trying to amplify the output voltage of a type K thermocouple that will be fed to an Arduino Uno. The main problem is I can't use any thermocouple modules (for eg Max 6675) or any instrumentation ...
2 votes
1 answer
173 views
Low-noise amplifier for microvolt signals with HV pulse immunity – offset compensation strategy?
I'm designing a low-noise amplifier for measuring very small differential voltages in the range of ±100 µV. Occasionally, the input may be exposed to short high-voltage (HV) pulses up to ±1 kV for a ...
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