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PGA112: PGA112: Will the PGA112 or other PGA be suitable for driving a low bandwidth signal into the THS4551 into a 24-bit Sigma Delta ADC?

Part Number: PGA112
Other Parts Discussed in Thread: OPA330, ADS127L01, INA333, THS4551

I have been evaluating the ADS127l01 (24-bit delta sigma adc) for the purpose of digitizing frequencies in the ~10-250 Hz bandwidth from a geophone

The eval board for the ADS127l01 drives the ADC with theTHS4551 differential amplifier. I am aiming for a dynamic range of 120 dB, 20 ENOB. (understandably idealistic goal)

This adc is being tested for portable, low power instrumentation and the wide band filter option is particularly useful. The cost per unit for the ADS1282 (seismic conditioning ADC with PGA, sinc filter, wideband filter etc.) is is too high for the volumes I need, Nevertheless, it is a phenomenal ADC+PGA for my application.

My price point requires an external PGA or at the very least a high quality fixed gain Operational Amplifier (I have been looking at the OPA330)

I have a few questions regarding this application:

1. Is the PGA112 a good choice to go directly into the THS4551 to drive the ADS127L01? If not, would more aggressive active filtering with the THS4551 cause a significant improvement?

2. Is there a PGA the fine T.I. engineers would recommend for my application?

3. One solution that comes to mind is the INA333 with a digitally controlled variable resistor, would this provide resolution and quality for driving the THS4551?

4. The OPA330 geophone preamplifier looks promising for a fixed gain amplification. Am I correct in this assumption? I would power the OPA330 with a single supply and apply 20x gain. DC shift between the rails and drive the THS4551. Would this solution be conducive to success?

Thank you, 

Sorry for so many question.