Interfacing OPAx387 with with Sensor VS45-H

[newbie_hs]

I am designing an acoustic emission sensor signal chain.

The sensor P/N is VS45-H. The signal chain is given below.

For buffer and amplifier I am planning to use OPAx387.

May I know your thoughts about this. Is OPAx387 is a good choice for this?

I have not decided any P/N for variable gain Amplifier.I think I can go with LMH6514SQ.

The DAQ may be an ADC present in the microcontroller(STM32) or will use a dedicated ADC and it's output will be processed by a uC.

May I know your thoughts about this entire signal chain.

 

[aliarifat794]

OPAx387 is a good choice. Confirm the input signal amplitude and frequency range of the VS45-H sensor to ensure the OPAx387's bandwidth and slew rate are sufficient.

 

[newbie_hs]

I received below information from sensor manufacturer.
"The VS45-H has no electronic inside, i.e. it will output the signal from the piezo inside the sensor. Typical noise value will be around 10 µV, the max. value for typical acoustic emission excitation up to 5V but it can be also higher:"

 

[KlausST]

Hi,

I did a lot of similar designs. And every single one was different.

If you go for low cost .. you would probably omit some stages.
If you go for low distortion .. you would place the BPF at the very beginning of the signal chain (this is to avoid the risk of overdriving the input stages of amplifiers by high frequency spikes)
If you go for low noise you would reduce the stages and make the signal paths low impedance, and put the BPF at the end of the chain.

What frequency range are you targeting?
And what are your requirements regarding, noise, distortion, dynamics ... ?
What information of the signal are you after?

You can´t get the optimum "for everything".

***
My recommendations:
(I´d say the first buffer stage can be omitted)
The first stage should be a high gain amplifier stage, with LPF/BPF included.
* LPF just to get rid of high dV/dt spikes
* BPF if you additionally want to get rid of DC
* high gain ensures high signal level making it less prone for (induced) noise

I´m not sure about the "gain control stage". Is the gain more expected to be >1 or <1 (like volume control pot). Why do you need it at all?

****
If you want us to give feedback about dedicated devices: post a link to the datasheets.

Klaus