Würth Elektronik 2022 15
DUT
LISN
EMI
reciever
conductive wall
non-conductive table
-20
0
20
40
60
80
100
100 kHz
dBµV
Average
150 kHz
-20
0
20
40
60
80
100
100 kHz 1 MHz
dBµV
Frequency
Average QPeak CISPR
150 kHz
-20
0
20
40
60
80
100
100 kHz 1 MHz
dBµV
Frequency
Average QPeak CISPR 32 Average
150 kHz
-20
0
20
40
60
80
100
100 kHz 1 MHz 10 MHz
dBµV
Frequency
Average QPeak CISPR 32 Average CISPR 32 QPeak
30 MHz
150 kHz
Figure 3: First EMC measurement with an aluminum electrolytic capacitor as C1 (Source: Würth Elektronik Group)
The EMC Measurement
Measurements were made according to the CISPR 32 standard
(which replaces CISPR 22 and 15) in an RF-shielded chamber with
the corresponding connection to the ground surface of the cabin
(Figure 2). The test receiver was an R&S ESRP 3, and as network
simulation, an ENV216 two-wire V-net simulation was available.
During the first step, further input filters on the layout were
dispensed. Only in the last measurement was a T-filter with a
separated coil placed. This filter was constructed according to
the specifications in the datasheet. For the first measurement, an
aluminum electrolytic capacitor WCAP-ASLL 865 060 343 004
was used for the input capacitor C1. The electrical properties of the
capacitor are as follows: Capacitance 47μF, rated voltage 16V with an
ESR 411mΩ and ESL 19nH. The associated measurement result is
shown in (Figure 3).
-20
0
20
40
60
80
100
100 kHz 1 MHz 10 MHz
dBµV
Frequency
Average QPeak CISPR 32 Average CISPR 32 QPeak
30 MHz
150 kHz
Figure 2: Setup of the EMC measurement according to CISPR 35 (Source: Würth Elektronik Group)
The unique feature of aluminum
electrolytic capacitors is using a
conductive polymer instead of a
liquid electrolyte.
"
