JAJSE67C December 2017 – June 2022 AMC1311
Placing an RC filter in front of the isolated amplifier improves signal-to-noise performance of the signal path. In practice, however, the impedance of the resistor divider is high and only a small-value filter capacitor can be used to not limit the signal bandwidth to an unacceptable low value. Design the input filter such that:
Most voltage-sensing applications use high-impedance resistor dividers in front of the isolated amplifier to scale down the input voltage. In this case, a single capacitor (as shown in Figure 9-2) is sufficient to filter the input signal.