PGA281
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SBOS664A –MARCH 2013–REVISED JUNE 2013
EMI Rejection
The PGA281 uses integrated electromagnetic interference (EMI) filtering to reduce the effects of EMI from
sources such as wireless communications, and densely-populated boards with a mix of analog signal chain and
digital components. The PGA281 is specifically designed to minimize susceptibility to EMI by incorporating an
internal low-pass filter. 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. 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 EMI rejection ratio (EMIRR) to quantify the PGA281 ability
to reject EMI. Figure 40 and Figure 41 show the PGA281 EMIRR graph for both differential and common-mode
EMI rejection across this frequency range. Table 2 shows the EMIRR values for the PGA281 at frequencies
commonly encountered in real-world applications. Applications listed in Table 2 may be centered on or operated
near the particular frequency shown.
180
160
140
120
100
80
160
140
120
100
80
60
60
40
40
20
20
0
0
10M
100M
Frequency (Hz)
1G
10G
10M
100M
Frequency (Hz)
1G
10G
C035
C036
Figure 40. Common Mode EMIRR Testing
Figure 41. Differential Mode (IN-P) EMIRR Testing
Table 2. PGA281 EMIRR for Frequencies of Interest
DIFFERENTIAL
(IN-P) EMIRR
COMMON-MODE
EMIRR
FREQUENCY
APPLICATION OR ALLOCATION
Mobile radio, mobile satellite, space operation, weather, radar,
ultra-high frequency (UHF) applications
400 MHz
84.3 dB
101.8 dB
125.6 dB
131.8 dB
122.4 dB
113.5 dB
123.3 dB
Global system for mobile communications (GSM) applications,
radio communication, navigation, GPS (to 1.6 GHz), GSM,
aeronautical mobile, UHF applications
900 MHz
1.8 GHz
2.4 GHz
3.6 GHz
5.0 GHz
103.3 dB
112.5 dB
114.6 dB
108.9 dB
118.7 dB
GSM applications, mobile personal communications, broadband,
satellite, L-band (1 GHz to 2 GHz)
802.11b, 802.11g, 802.11n, Bluetooth®, mobile personal
communications, industrial, scientific and medical (ISM) radio band,
amateur radio and satellite, S-band (2 GHz to 4 GHz)
Radiolocation, aero communication and navigation, satellite,
mobile, S-band
802.11a, 802.11n, aero communication and navigation, mobile
communication, space and satellite operation, C-band (4 GHz to 8
GHz)
Copyright © 2013, Texas Instruments Incorporated
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