AnsweredAssumed Answered

instrumentation amplifier configuration

Question asked by ALIREZA7 on Apr 6, 2018
Latest reply on Apr 10, 2018 by ALIREZA7


first of all my application is based on these articles :

Electromagnetic Flow Meters Achieve High Accuracy in Industrial Applications | Analog Devices 

Electromagnetic Flow Meters: Design Considerations | Analog Devices 


i want to configure an instrumentation amplifier in order to amplify the induced signal of my electrode probes and i encountered this problem :


if i want to have an ac coupled input then i should use a resistor from each input to the ground for dc bios current return path. as illustrated in this picture:

this configuration will reduce input impedance which have contradict with one of the reasons of using an in-amp (having a G ohm input impedance) . but i saw some circuits that use this configuration for this application .


the other possible configuration is the one introduced in the articles that i mentioned above which is a dc coupled configuration . in those articles analog devices suggested to connect electrodes directly to the input of in amp.

but indeed am not sure about using a dc coupled configuration (my main reason is that i think if the measuring liquid have a high dc voltage imposed by operating environment it may damage the in-amp).


I still could not choose between these two configurations(or any other configurations if there is).


i would be grateful for any help that makes me able to configure my in amp in the best way .