[NOTES]
-24-
1.EMI Suppression Filters for DC Applications
This is the PDF file of text No. TE05EY-2. TE05EY-2.pdf 98.03.20
1.7.Examples of Improving Noise Suppression on Power Supply Lines
Bypass capacitor in a power supply line not only supplies tran-
sient current necessary to change signals to IC, but also sup-
presses the generation and conduction of power supply line noise.
When a three-terminal capacitor is used as a bypass capacitor
and/or an inductor is added, the noise generated in the power sup-
ply line can be suppressed significantly more than when only a
two-terminal capacitor is used.
24
Examples of Improving Noise
Suppression on Power Supply Lines
+
NFM41P
0 100 200 300 400 500
Frequency(MHz)
70
60
50
40
30
20
0 100 200 300 400 500
Frequency(MHz)
70
60
50
40
30
20
0 100 200 300 400 500
Frequency(MHz)
70
60
50
40
30
20
BLM11P600S
Level (dBµV)Level (dBµV)Level (dBµV)
MTest circuit
MUsing a two-terminal capacitor
Chip monolithic capacitor (1µF)
MUsing a three-terminal capacitor
NFM41P
0.2µF
MAdd an SMT ferrite bead
22µF+
VCC(+5V)
GND
Measure point
Ceralock
1µF
HCU04
1µF
HC04
Oscillator section Noise sourece
5MHz
1µF
Load
HC00
NFM41P
BLM11P600S
Change to three-terminal capacitor
/with SMT ferrite beads
Spectrum
