7.3.2 EMI Rejection

Texas Instruments developed a method to accurately measure the immunity of an amplifier over a broad frequency spectrum, extending from 10 MHz to 6 GHz. This method uses an EMI rejection ratio (EMIRR) to quantify the ability of the INA828 to reject EMI. The offset resulting from an input EMI signal can be calculated using Equation 2:

Equation 2.

where

• V_{RF_PEAK} is the peak amplitude of the input EMI signal.

Figure 53 and Figure 54 show the INA828 EMIRR graph for both differential and common-mode EMI rejection across this frequency range. Table 2 shows the EMIRR values for the INA828 at frequencies commonly encountered in real-world applications. Applications listed in Table 2 can be centered on or operated near the particular frequency shown. Depending on the end-system requirements, additional EMI filters may be required near the signal inputs of the system, as well as incorporating known good practices such as using short traces, low-pass filters, and damping resistors combined with parallel and shielded signal routing.

Figure 53. Common-Mode EMIRR Testing

Figure 54. Differential Mode EMIRR Testing