OPA2188: Suitability for micro voltage inputs

ASHWIN SHARMA

Part Number: OPA2188
Other Parts Discussed in Thread: ADS1299, , OPA2387, OPA2388, TLV2387, OPA4387, INA333

Tool/software:

Hello,

We are currently in the process of designing the EEG data acquisition system using ADS1299, and we are considering using a pre-amplifier OPA2188.

We have some questions regarding its suitability for micro voltage inputs (EEG signals) and its output range. Additionally, we would like to know how to adjust the gain of the device and what makes OPA2188 a suitable choice for the pre-amplifier of the EEG data acquisition system. "Please recommend a suitable preamplifier for an EEG data acquisition system."

Thank you.

24 days ago

0 Clemens Ladisch 24 days ago

Guru 258480 points

Please specify the input and output voltage ranges, the highest signal frequency, and what errors you can afford.

(An opamp's input offset error is added to the input signal, and is amplified at the output. To compute the maximum frequency, divide the GBW by the gain.)

0 Raymond Zhang1 24 days ago

TI__Guru 51561 points

Hi Sharma,

I would suggest 5V precision op amp, rather than 36V op amp. Below is some of the guideline. You may consider OPA2387, TLV2387, OPA2388 or similar low drift, low noise, low Iq and Vos, high CMRR & PSRR op amps etc..

The EEG reference guide is a good resource, but my guess is that the component selections are not up to date. You may find better op amps and related IC for the application.

file:///C:/Users/cits2/Downloads/ECG%20an%20EEG%20Applications.pdf

https://www.ti.com/amplifier-circuit/op-amps/precision/products.html#480=2&2192=Zero%20Drift&1261max=3.6%3B5.5&

https://www.ti.com/lit/ds/symlink/afe4900.pdf?ts=1719388207658

https://www.ti.com/data-converters/integrated-special-function/medical-afes/biosensing-afes/overview.html

If you have other questions, please let us know.

Best,

Raymond

0 ASHWIN SHARMA 23 days ago in reply to Clemens Ladisch

Prodigy 30 points

Hi,

The input is in microvolts (μV) from 10μV to 100μV; the signal frequency ranges from about 0.1 to 100 Hz

+1 Clemens Ladisch 23 days ago in reply to ASHWIN SHARMA

Guru 258480 points

Amplifying 100 µV to 5 V requires a gain of 50000, so with 100 Hz signals, you require a GBW of at least 5 MHz. See Raymond's recommendations; there also are four-channels versions (OPA4387 etc.).

If you want to read a 10 µV signal, then the Vos should be much smaller. So the OPAx387 with 2 µV would be the best choice.

0 Raymond Zhang1 23 days ago in reply to ASHWIN SHARMA

TI__Guru 51561 points

Hi Sharma,

In addition to Clemens comments, you may consider the instrumentation amplifier, INA333 was very popular in that application, but we have tons of instrumentation to choose from.

0743.ECG an EEG Applications.pdf

https://www.ti.com/amplifier-circuit/instrumentation/products.html

For the application, you may need to calibrate the Vos errors, and improve CMRR, which IA is the one of the best option.

Best,

Raymond

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OPA2188: Suitability for micro voltage inputs