INA326: Instrumentation amplifier recommendation

Roberto Duralde

Part Number: INA326
Other Parts Discussed in Thread: INA114, INA826, INA828

Hello there!

Sorry to bother you with such a simple group of questions, but I'm pretty new to this biomedical world. Turns out I designed an EMG amplifier with the INA114, but had the problem that it couldn't operate in single supply mode, so I need to make a little upgrade to the system. My question actually is, which precision amplifier do you recommend for such a task. I've looked around but there are a lot of them and I'd prefer to ask for an expert opinion on the matter. It seems that the INA326 is a good choice for the task, and can operate in single supply mode, any opinions on this amplifier?

This leads to my other question, and this is totally because of lack of experience. Reading the forums, I see people connecting the reference pin on the INA to Vcc/2 instead of ground. Is this mandatory when operating on single supply? I'm assuming it's for the output to be able to swing safely. In this case, the reference electrode should still be connected to this reference pin? Or should it go directly to ground?

Sorry again for such simple questions!

Roberto

over 5 years ago

0 kai klaas69 over 5 years ago

Guru 140200 points

Hi Roberto,

the datasheet of INA826 contains useful information.

Kai

0 Roberto Duralde over 5 years ago in reply to kai klaas69

Prodigy 120 points

It indeed does! Thank you!

0 Zak Kaye over 5 years ago in reply to Roberto Duralde

TI__Mastermind 23050 points

Hi Roberto,

You may find the attached presentation on ECGs useful as well. It goes into detail about the design considerations and choosing a device. The principles should be applicable to your EMG.

Additionally, here is a tool for INAs that determines what your limitations are based on your supplies and common-mode range: www.ti.com/.../INA-CMV-CALC

The INA826 and INA828 are some of our newest devices that are well suited to this task, but when operating in single supply you generally need a reference voltage to keep the output in the linear region. There are also common-mode input limitations. For most INAs you also cannot ground one of the inputs in a single supply configuration because this saturates the internal front end amplifier, as it is unable to swing all the way to the negative supply. The INA326 has a different topology that can accommodate inputs that extend beyond the supplies , but you must still keep the output limitations in mind.

ECG_Fundamentals_condensed.ppt

0 Roberto Duralde over 5 years ago in reply to Zak Kaye

Prodigy 120 points

Thank you! I'll give it a look.

Roberto

0 Dennis Goeke over 5 years ago in reply to Roberto Duralde

TI__Genius 11135 points

Roberto

We haven't heard back from you so we assume this answered your questions. If you need more help just post a reply below.

Thanks
Dennis

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INA326: Instrumentation amplifier recommendation