Electromagnetic interference rejection ratio (EMIRR) is a measure of how high frequency signals that are outside of the op amps bandwidth can impact V_OS. Specifically, the EMIRR test directly couples a sinusoidal waveform with frequency ranging from 10 MHz to 10 GHz and looks at the shift in V_OS. It may seem unusual that a DC parameter such as offset is affected by signals outside the bandwidth of the amplifier. However, this high-frequency AC input signal undergoes a rectification by internal diodes and is converted from a high frequency AC signal to a change in DC operation of the amplifier (V_OS). This test can be thought of as a conducted immunity test. The details of how the EMIRR is tested is covered in EMI Rejection Ratio of Operational Amplifiers.

Figure 3-10 shows the graph of EMIRR for OPA206. As an example, assume a 40 mVpk, 100 MHz noise signal is applied to the noninverting input of the amplifier. The shift in V_OS can be calculated to be 90 µV using Equation 35.

Figure 3-10 EMIRR vs Frequency for OPA206