Hello,

I have a question about the Figure 86, page 317 from UG-587. Into the explanation is said "The excitation buffer forces the output voltage D to be equal to the differential voltage across the sensor, P-N". What does it give us like benefit. Can someone explain in more details the idea of these P and N feedbacks.

Thank you

I'm not sure if I fully understand your question, so please let me know if I don't answer correctly.

The voltage across the sensor remains constant (this is done by using the P and N nodes to measure the voltage), only the current will change. The current that flows is dependent on the impedance to be measured (e.g. RC). The current that flows into the TIA will be a direct linear correlation between the fixed voltage and the measured impedance. The TIA will convert this current to a voltage. For an impedance measurement, the ADC will take 2048 samples, which are processed by the DFT block to produce a real and imaginary representation of the measured impedance.