Operational amplifiers vary in susceptibility to electromagnetic interference (EMI). If conducted EMI enters the operational amplifier, the dc offset observed at the amplifier output can shift from the nominal value while EMI is present. This shift is a result of signal rectification associated with the internal semiconductor junctions. While all operational amplifier pin functions can be affected by EMI, the input pins are most likely susceptible. The OPA3S328 operational amplifiers incorporate an internal input low-pass filter that reduces the amplifiers response to EMI. Both common-mode and differential-mode filtering are provided by the input filter. Figure 8-2 shows the amplifier EMIRR response.

Figure 8-2 OPA3S328 EMIRR Response