Filtering conducted RF-EMI 50/60Hz ac line filter example

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Filtering conducted RF-EMI50/60Hz ac line filter
example
Common-mode inductor
Mode 150kHz 500kHz 1MHz 5MHz 10MHz 20MHz 30MHz
Common 6 20 28 42 45 45 48 dB
Differential 10 13 30 50 50 40 40 dB
Attenuation characteristics for ac line filter
(SAE GA1B-10)
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Input RC filtering as applied to an
instrumentation amplifier
Y Y
X
Capacitors X 2Y
Differential Mode f-3dB 2p(RA RB)(CA
CB/2)-1 let RB RA and CC CB f-3dB 343Hz
Common Mode f-3dB 2pRA CB)-1 let RB RA
and CC CB f-3dB 7.2kHz
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X2Y Capacitor Architecture

• The X2Y capacitor
• 1 X capacitor, 2 Y capacitors
• Effective for both common-mode and
• differential-mode filtering
• Excellent capacitance matching

G1
A
B
G2
Cx ½ Cy
terminations
From Yageo.com website
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The X2Y capacitor in application
X2Y Filter Decoupling Capacitors
Input filtering s21 Signal-to-Ground
10nF
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Newer op-amps have built-in EMI filtering