I try to feed the EVAL-AD7357EDZ with a signal between 100KHz and a few MHz (with an estimated amplitude of micro volts) coming from a piezo-electric transducer of high impedance (more than 100MOhm). I suspect this fails because there is a significant impedance mismatch between the transducer and the ADC and because my signal is too low.
I am thinking to use a low noise preamplifier (something similar to AD797). Is there any evaluation board which has input impedance in the range of 10 MOhm to 1GOhm? Is there any possibility to modify one? (your lights please)
Thank you very much Emmanuel for your answer.
Actually I was thinking not to modify something on the existing EVAL-AD7357EDZ but to have the appropriate evaluation board additionally which will play the role of a pre-amplifier. Do you think that this can be realized by the EVAL-PRAOPAMP evaluation board? I am asking because it seems that all, i.e., AD8591, ADA400 and AD8661, which you suggest perfectly suit my needs.