INA 126

Vineet Gupta

Other Parts Discussed in Thread: LM358

Hello TI

I am working on a EMG sensor. I am using INA 126 in first stage to amplify the EMG signals with gain 5. Then an amplifier( inverting ) using IC LM358 with gain 1000 is used as second stage. I am using a 5 volts dual supply for the circuit by stepping down two 9V batteries.I m using SMD components but still getting noise of around 100mV RMS. plz help me to reduce noise.

over 13 years ago

0 Art Kay over 13 years ago

TI__Mastermind 25428 points

6215.noise_emg_sensor.pdfVineet,

I did a quick calculation and I estimate that you should get about 53mV p-p at the output of your amplifier. (see attachment). So you are reading higher noise that I estimate but the difference is not huge. The difference could be accounted for by noise from your sensor which was not included in my analysis. Based on your measurements I think the circuit is working as expected.

There are two main ways that you can reduce the noise. 1) You can further limit the bandwidth. 2) You can use a different instrumentation amplifier that has lower noise. Also you may want to repartition the gain so that the instrumentation amplifier has higher gain. More gain on the input stage takes advantage of the high end input stage.

I have a book and article series on this subject. See links below.

Book: Operational Amplifier Noise

http://www.amazon.com/Operational-Amplifier-Noise-Techniques-ebook/dp/B00755CRB8/ref=dp_kinw_strp_1?ie=UTF8&m=AG56TWVU5XWC2

Article Series: Intrinsic Noise

http://www.en-genius.net/site/zones/audiovideoZONE/technical_notes/avt_012312

Art Kay

Amplifiers

Amplifiers forum

INA 126