Espiridion

Good morning, We have an on-board system (DC-DC converter, UPS, PC,sensors..etc) and as one of the system sensors the piezoelectric PCB PIEZOTRONICS Model 352C03, and apparently when doing a test we have seen that when biasing the system with a low frequency AC signal (80-1000 MHz) the sensors (piezoelectric) mentioned above begin to give random values and that is why the system does not work correctly, although at high frequencies it does perform its function. We have two options, or the problem is on the piezoelectric or on the DT9837 piezoelectric digitalizer . There is nothing related to this in the product specifications. Could you tell me who is the one who fails and why? Why could AC low frequency signal affect the piezoelectric or the digitalizer? Thanks,