Frequency (Hz)

0

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140

10M

100M

1G

10G

Frequency (Hz)

0

20

40

60

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120

10M

100M

1G

10G

EMIRR (dB)

2

RF _ PEAK

20

OS

P

V

V

10

100 mV

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22

INA821

SBOS893A – AUGUST 2018 – REVISED DECEMBER 2018

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Product Folder Links: INA821

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Copyright © 2018, Texas Instruments Incorporated

8.3.2 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 INA821 to reject EMI. The offset resulting from an input EMI signal is calculated using

Equation 2:

where

•

(2)

Figure 56 and Figure 57 show the INA821 EMIRR graph for differential and common-mode EMI rejection across

this frequency range. Table 3 shows the EMIRR values for the INA821 at frequencies encountered in real-world

applications. Applications listed in Table 3 are 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 56. Common-Mode EMIRR Testing

Figure 57. Differential Mode EMIRR Testing