EMC Test Specification for BroadR-Reach® Common Mode …...Author & Company Dr. Bernd Körber, FTZ Zwickau Title EMC Test Specification for BroadR-Reach® Common Mode Chokes Version

EMC Test Specification for BroadR-Reach® Common

Mode Chokes Version 2.0

Author & Company Dr. Bernd Körber, FTZ Zwickau

Title EMC Test Specification for BroadR-Reach® Common Mode Chokes

Version 2.0

Date December 19, 2014

Status Final version

Restriction Level Public

This measurement specification shall be used as a standardized common scale for EMC evaluation of common mode chokes for 100 Mbit/s BroadR-Reach® in automotive applications.

OPEN Alliance

Restriction Level: Public | EMC Test Specification for BroadR-Reach® Common Mode Chokes | Dec-14 2

Version Control of Document

Version Author Description Date

0.1 B. Körber Initial version 10/23/12

0.2 B. Körber 2cd draft version

discussed changes from telco OA TC1

changed to new OA document template

section “Attenuation at ESD discharge“ removed

recommended limits added in Appendix

07/08/13

1.0 B. Körber 3rd draft version

software configuration for test Transceiver updated

recommended limits for S-Parameter added

recommended limits for RF immunity and RF emission changed

24/09/13

1.1 B. Körber Disclaimer added 10/04/13

1.2 B. Körber Limit return loss changed Change of reference transceiver

09/14/14

1.3 B. Körber Definition for optimized BIN changed 10/02/14

2.0 B. Körber Numbering of version changed 12/19/14

Restriction level history of Document

Version Restriction Level Description Date

0.1 Open internal only 10/23/12




1.2 Public 09/14/14

1.3 Public 10/02/14

2.0 Public 12/19/14

OPEN Alliance


Disclaimer

The OPEN Specifications (including any part thereof) are intended to be used as an information source to

enable to manufacture and test products which comply with the OPEN Specification.

All OPEN Specifications are provided on “as is” basis and all warranties, either explicit or implied, are

excluded unless mandatory under law. Accordingly, the OPEN Alliance Members who have contributed to

the OPEN Specifications make no representations or warranties with regard to the OPEN Specifications or

the information (including any software) contained therein, including any warranties of merchantability,

fitness for purpose, or absence of third party rights and make no representations as to the accuracy or

completeness of the OPEN Specifications or any information contained therein.

The OPEN Alliance Members who have contributed to the OPEN Specifications will not be liable for any

losses, costs, expenses or damages arising in any way out of use or reliance upon any OPEN Specification

or any information therein. Nothing in this document operates to limit or exclude any liability for fraud or

any other liability which is not permitted to be excluded or limited by operation of law.

The material contained in OPEN Specifications is protected by copyright and may be subject to other types

of Intellectual Property Rights. OPEN Specifications (or any part thereof) shall be distributed only among

those bound by the confidentiality defined for the OPEN Specification and as announced in the OPEN

Specification documents.

The distribution of OPEN Specifications shall not operate as an assignment or license to any recipient of

any OPEN Specification of any patents, registered designs, unregistered designs, trademarks, trade names

or other rights as may subsist in or be contained in or reproduced in any OPEN Specification. The

commercial exploitation of the material in this document may require such a license, and any and all

liability arising out of use without such a license is excluded.

OPEN Specification documents may be reproduced in electronic or paper form or utilized in order to

achieve the Scope only. Reproduction or utilization for any other purposes as well as any modification of

the Specification document, in any form or by any means, electronic or mechanical, including

photocopying and microfilm, is explicitly excluded.

Without prejudice to the foregoing, the OPEN Alliance Specifications have been developed for automotive

applications only. They have neither been developed, nor tested for non-automotive applications.

OPEN Alliance reserves the right to withdraw, modify, or replace any OPEN Specification at any time,

without notice.

OPEN Alliance


Contents 1 Introduction .......................................................................................................................................... 5

1.1 Scope ............................................................................................................................................. 5

1.2 References .................................................................................................................................... 5

1.3 List of abbreviations and definitions ............................................................................................. 6

2 Required Tests ...................................................................................................................................... 7

2.1 General .......................................................................................................................................... 7

2.2 Mixed mode S-Parameter measurement ..................................................................................... 8

2.2.1 Test setup .............................................................................................................................. 8

2.2.2 Test procedure and parameters ........................................................................................... 9

2.3 TDR measurement of differential mode impedance .................................................................. 11

2.3.1 Test setup ............................................................................................................................ 11

2.3.2 Test procedure and parameters ......................................................................................... 12

2.4 Damage from ESD ....................................................................................................................... 13

2.4.1 Test setup ............................................................................................................................ 13


2.5 Common test conditions for tests in combination with a BroadR-Reach® transceiver .............. 15

2.6 Increase in RF immunity of interface network ............................................................................ 16

2.6.1 Test setup ............................................................................................................................ 16


2.7 Decrease in RF emission of interface network ........................................................................... 18

2.7.1 Test setup ............................................................................................................................ 18


Appendix A - Test circuit boards ................................................................................................................. 20

A.1 Example for test fixture S-Parameter measurement .................................................................. 20

Appendix B – Recommended limits for tests .............................................................................................. 21

B.1 S-Parameter measurements ....................................................................................................... 21

B.2 Damage from ESD ....................................................................................................................... 23

B.3 Increase in RF immunity of interface network ............................................................................ 23

B.4 Decrease in RF emission of interface network ........................................................................... 24

OPEN Alliance


1 Introduction

1.1 Scope

This measurement specification shall be used as a standardized common scale for EMC evaluation of

common mode chokes (CMCs) intended to use with 100 Mbit/s BroadR-Reach® in automotive applications

according to [OPEN1]. It contains recommended limits. The final judgment of the tested device is left to

the customer.

Several tests are based on [OPEN2]. For these tests all definitions of [OPEN2] are valid.

This specification is not applicable for devices that are intended for use in Power over Data Line

applications.

This instruction includes test procedures and test setups concerning:

Mixed mode S-Parameter measurement

TDR measurement of differential mode impedance

Test of damage from ESD

Test the increase in RF immunity of a defined BroadR-Reach® interface network

Measuring the decrease in RF emission of a defined BroadR-Reach® interface network.

1.2 References

[OPEN1] Broadcom / OPEN Alliance BroadR-Reach® (OABR) Physical Layer Transceiver Specification For Automotive Applications, Version 3.2

[OPEN2] OPEN ALLIANCE: EMC Test Specification for BroadR-Reach® Transceivers, Version 1.3

[IEC1] IEC 61967-1, Integrated circuits, Measurement of electromagnetic emissions, 150 kHz to 1 GHz – Part 1: General and definitions

[IEC2] IEC 61967-4, Integrated circuits, Measurement of electromagnetic emissions, 150 kHz to 1 GHz – Part 4: Measurement of conducted emissions – 1 Ω/150 Ω direct coupling method

[IEC3] IEC 62132-4, Integrated circuits, Measurement of electromagnetic immunity, 150 kHz to 1 GHz – Part 4: Direct RF power injection method

[IEC4] IEC 61000-4-2, Electromagnetic compatibility, Part 4-2: Testing and measurement techniques – Electrostatic discharge immunity test

OPEN Alliance


1.3 List of abbreviations and definitions

AM Amplitude Modulation

BIN MDI Test Network

CDMR Common to Differential Mode Rejection, common mode single ended measured

CMC Common Mode Choke

CMR Common Mode Rejection

CW Continuous Wave

DCMR Differential to Common Mode Rejection, common mode single ended measured

DPI Direct Power Injection

ESD Electro Static Discharge

IL Insertion Loss

PM Pulse Modulation

LPF Low Pass Filter

RF Radio Frequency

RL Return Loss

S-Parameter Scattering Parameter

TDR Time domain reflection

VNA Vector Network Analyzer

OPEN Alliance


2 Required Tests

2.1 General

For evaluation of EMC behavior of the CMC two groups of tests are defined:

1. Passive component tests:

Mixed mode S-Parameter

TDR

Damage from ESD

2. Tests in combination with a BroadR-Reach® transceiver:

Test the increase in RF immunity

Measuring the decrease in RF emission

Prior to performing any TDR, ESD and RF tests, the S-Parameter measurements shall be performed on a

minimum of 10 samples. Based on these results, 3 groups of 2 samples each shall be selected and used

for the remaining tests. The groups are:

best case sample

worst case sample

typical sample.

The main criteria for selection of CMC into groups are the S-Parameter Sdd11 and Ssd21.

OPEN Alliance


2.2 Mixed mode S-Parameter measurement

2.2.1 Test setup

For measuring the mixed mode S-Parameters a 4-port VNA in combination with a special test fixture

(adapter test board) shall be used. The test fixture has to be included into the test setup during calibration

of VNA test setup. The calibration points are defined to the pads of the CMC at the test fixture board.

VNA

Test fixture

Network analyzer

DUT 1 Calibration

points

1

1

Figure 2-1: Test setup for S-Parameter measurements

Test equipment requirements:

Network analyzer: 4-port vector network analyzer

f = 0.3 - 1000 MHz (in minimum)

Test fixture: according to Appendix A

OPEN Alliance


2.2.2 Test procedure and parameters

The required measurements are defined in Table 2-1.

Parameter Description

Frequency range: 300 kHz to 1 GHz

S-Parameter per single

path:

Sdd11 (RL), log. Magnitude in dB / transceiver side

Sdd22 (RL), log. Magnitude in dB / connector side

Sdd21 (IL), log. Magnitude in dB / transceiver side

Scc21 (CMR), log. Magnitude in dB / transceiver side

Ssd21 (DCMR), log. Magnitude in dB / transceiver side

Ssd12 (DCMR), log. Magnitude in dB / connector side

Sds21 (CDMR), log. Magnitude in dB / transceiver side

Sds12 (CDMR), log. Magnitude in dB / connector side

VNA measurement circuit: Port definitions:

Mixed mode logic port 1: physical port 1 and port 2 / transceiver side

Mixed mode logic port 2: physical port 3 and port 4 / connector side

Pin 1 of CMC is placed on transceiver side (logic port 1)

Sdd11, Sdd22, Sdd21, Scc21 measurement:

50 Ω input impedance at each measurement port

VNA Port 1

(50 Ohm)

VNA Port 2

(50 Ohm)

DUT

VNA Port 3

(50 Ohm)

VNA Port 4

(50 Ohm)

1

Ssd21 measurement:

differential mode input: 50 Ω impedance each

common mode output: single ended network with symmetrical

network:

Single ended VNA Port 3

(50 Ohm)

75

50

50

VNA Port 1

(50 Ohm)

VNA Port 2

(50 Ohm)

DUT

1

R = (2 x 50 ) +75

OPEN Alliance


Note: The accuracy of resistor values should by 1 %. The difference

between matching resistors should be 0.1 %.

For Ssd12 measurement the terminal orientation of the CMC must

be flipped at the test board.

Sds12 measurement:

common mode input: single ended network with symmetrical

network:

Single ended VNA Port 3

(50 Ohm)

75

50

50

VNA Port 1

(50 Ohm)

VNA Port 2

(50 Ohm)

DUT

1

R = 75 + (2 x 50 )

Note: The accuracy of resistor values should by 1 %. The difference

between matching resistors should be 0.1 %.

differential mode output: 50 Ω impedance each

For Sds21 measurement the terminal orientation of the CMC must

be flipped at the test board.

Table 2-1: Test parameters for S- Parameter measurements

The measurements shall be performed and documented according the scheme given in Table 2-2.

Test S- Parameter Sample

S1 Sdd11 (RL)

10 samples each

S2 Sdd22 (RL)

S3 Sdd21 (IL)

S4 Scc21 (CMR)

S5 Ssd21 (DCMR)

S6 Ssd12 (DCMR)

S7 Sds21 (CDMR)

S8 Sds12 (CDMR)

Table 2-2: Required S-Parameter measurements

For each test case the results for all 10 samples has to be documented as diagram in the test report.

Recommended limits for evaluation are given in Appendix B.1.

OPEN Alliance


2.3 TDR measurement of differential mode impedance

2.3.1 Test setup

For measuring the differential mode impedance of the CMC a two-channel TDR test equipment in

combination with a special test fixture (adapter test board) shall be used.

Test fixture

TDR test equipment

DUT

Figure 2-2: Test setup for TDR measurements


TDR measurement

system:

Type: 2 channel differential mode

System impedance: 50 single ended / 100 differential mode

Rise time: 25 ps internal ( 100 ps at test fixture)

Test fixture: Use test fixture from 4 port S-Parameter measurements

OPEN Alliance



The required measurements are defined in Table 2-3 and should be done on one sample. This sample

should be a typical sample, selected by S-Parameter measurements according to section 2.2.


TDR measurement circuit: Definition:

Pin 1 of CMC is placed on the transceiver side (TDR measurement port)

TDR Port 1

(50 Ohm)

TDR Port 2

(50 Ohm)

DUT

Termination to GND

(open/50 Ohm)

Termination to GND

(open/50 Ohm)

1

Note: The TDR shall be deskewed at the CMC terminals.

Table 2-3: Test parameters for TDR measurements

The measurements shall be performed and documented according the scheme given in Table 2-4.

Test Parameter Sample

T1 Differential mode impedance 1 typical sample

Table 2-4: Required TDR measurements

There is no recommendation for limit. This test is only for information purpose and can be used for

additional interpretation of results of S-Parameter measurements.

OPEN Alliance


2.4 Damage from ESD

2.4.1 Test setup

The setup given in Figure 2-3 shall be used for testing the ESD robustness of CMC. This test setup is based

on definitions of [OPEN2], section ESD tests.

ESD Test board

GND Discharge points DP1, DP2

Ground plane ESD Test board

Connection point Ground plane

Test generator with contact discharge module

ESD Simulator

Ground reverse line Test generator

connection loads to Ground plane ESD Test board

Ground plane (minimal 0.5 x 0.5 m)

ESD Test board

fixture

Surface connection ESD Test board to Test board support

Surface connection Test board fixture to ground plane

R1

R2

Load resistors Common mode choke

Figure 2-3: Test setup for ESD damage tests

The ground plane with a minimum size of 0.5 x 0.5 m builds the reference ground plane for the ESD Test

setup and must be connected with the electrical grounding system of the test laboratory. The ESD Test

generator ground cable shall be connected to this reference plane. The test board fixture realizes the

positioning of the ESD Test board and the electrical connection of the ESD Test board ground plane with

the reference ground plane. This connection must have low impedance (R < 25 m) and should be built

by a surface contact.

During testing the tip of the ESD Test generator discharge module shall be directly contacted with one of

the discharge pads DP1 or DP2 of the ESD test board. For this purpose, the discharge points DP 1 and DP2

are implemented as rounded vias in the layout of the ESD test board and are directly connected by a trace

15 (-0 +5) mm with the respective pin of the CMC.

OPEN Alliance


Test Equipment Requirements:

ESD test generator: according to [IEC4]; contact discharge module with

discharge capacitor 150 pF and discharge resistor

330

ESD test board: according to [OPEN2]


The required tests are defined in Table 2-5 and should be done on one sample. This sample should be a

typical sample, selected by S-Parameter measurements according to section 2.2.


Coupling of ESD: direct galvanic coupled using a Contact Discharge Module according to

[IEC4] (C = 150 pF, R = 330 )

Test circuit:

Note: All resistors shall be from the SMD design 1206 or 0805 with a

maximum tolerance of 1 %. The exact type ID and manufacturer of the used

resistors must be documented in the test report.

ESD test voltage: 8 kV

Number of discharges: 10 per polarity

Time between discharges: 5 s

Damage evaluation

criteria:

Maximum deviation of 5 % from the original value after performing

the tests:

Series resistance of line 1 and 2: RS1, RS2

Isolation resistance line 1 to line 2: RISO )1

Inductivity line 1 and 2: LS1, LS2 )2

)1 Measurement at +100 V DC test voltage for 2 s )2 Measurement at f = 1 MHz

Test procedure: 1. Apply ESD discharges at DP1 ( 8 kV, 10 per polarity, 5 s delay)

2. Apply ESD discharges at DP2 ( 8 kV, 10 per polarity, 5 s delay)

3. Evaluate damage using damage evaluation criteria

Table 2-5: Test parameters for ESD damage tests

The tests shall be performed and documented according the scheme given in Table 2-6.

OPEN Alliance


Test Discharge points

Comment Sample

E1 DP1 Line 1 one typical

sample each E2 DP2 Line 2

Table 2-6: Required ESD tests for damage

The CMC must withstand the ESD discharge without damage according to the damage evaluation criteria.

Recommended limits are given in Appendix B.3.

2.5 Common test conditions for tests in combination with a BroadR-Reach®

transceiver For all test of EMC behavior of the CMC in combination with a BroadR-Reach® transceiver according to

[OPEN1] an Ethernet test network consisting of two bus nodes according to [OPEN2] has to be set up. It

shall be done using two different MDI test networks (BIN) - according to Figure 2-4 for BroadR-Reach®

interface with standard MDI interface network and according to Figure 2-5 for BroadR-Reach interface

with optimized MDI interface network.

Figure 2-4: Test circuit diagram for DPI tests for BroadR-Reach® interface with standard MDI interface network

Figure 2-5: Test circuit diagram for DPI tests for BroadR-Reach® interface with optimized MDI interface network

OPEN Alliance


2.6 Increase in RF immunity of interface network

2.6.1 Test setup

The increase in RF immunity of interface network caused by the CMC shall be measured using the DPI test

method according to [IEC3] and [OPEN2]. The general test setup is illustrated in Figure 2-6. The forward

RF power shall be used for test level definition.

Monitoring

DSO

Test board External voltage supply

Testing: MDI RF1

RF1

Host µC board RF TC board

RF Generation

Power meter

RF Generator

RF Amplifier

Control PC

Figure 2-6: Test setup for DPI tests


RF Generator: f = 1 - 1000 MHz, including amplitude and pulse modulation

RF Amplifier: PCW 10 W

RF Power meter with

directional coupler:

f = 1 - 1000 MHz

Test board: according to [OPEN2]

DSO

External voltage supply

Control PC

OPEN Alliance



The tests are based on the definitions of [OPEN2] for the DPI tests with the additional definitions given in

Table 2-7.


Modulation: AM 80 %, 1 kHz / PM 217Hz, ton 577µs

Maximum test power: 39 dBm

Transceiver type and

configuration:

The used transceiver must be in line with definitions of [OPEN1] and

[OPEN2]. The used configuration for the transceiver should be in-line

with tests according to [OPEN2].

Optimized MDI test

network configuration:

Should be in-line with tests of used transceiver according to [OPEN2].

Communication test

signal:

according to [OPEN2]

Failure validation: Sum error according to [OPEN2]

Table 2-7: Test parameters for DPI tests

The tests shall be performed and documented according the scheme given in Table 2-8.

Test MDI test network (BIN)

Type of coupling on MDI pins

Coupling resistors

Sample

R1

[]

R2

[]

D1

standard

symmetric 120 120

Set of 2 samples of each group (best case /

typical / worst case)

D2 + 2.5 % unbalanced 121 118

D3 - 2.5 % unbalanced 118 121

D4

optimized

symmetric 120 120

D5 + 2.5 % unbalanced 121 118

D6 - 2.5 % unbalanced 118 121

Table 2-8: Required DPI tests

For each test case an immunity threshold curve with the forward power as the parameter has to be carried

out and presented in the test report in a diagram. Recommended limits are given in Appendix B.3.

OPEN Alliance


2.7 Decrease in RF emission of interface network

2.7.1 Test setup

The decrease in RF emission of interface network caused by the CMC shall be measured by conducted

emission measurement method (150 Ohm test method) according to [IEC2] and [OPEN2]. A general test

setup is illustrated in Figure 2-7.

Monitoring

DSO

RF Analyzer

Test board External voltage supply

Measuring: MDI EMI1

EMI1

Host µC board RF TC board

Figure 2-7: Test setup for measurement of RF disturbances on MDI


RF Analyzer: Spectrum analyzer or measuring receiver according to [IEC1]

Test board: according to [OPEN2]

External voltage supply

OPEN Alliance



The tests are based on the definitions of [OPEN2] for the 150 measurement method with the additional

definitions given in Table 2-9.


Transceiver type and

configuration:

The used transceiver must be in line with definitions of [OPEN1] and

[OPEN2]. The used configuration for the transceiver should be in-line

with tests according to [OPEN2]

Optimized MDI test

network configuration:

Should be in-line with tests of used transceiver according to [OPEN2].

Communication test

signal:

according to [OPEN2]

Table 2-9: Test parameters for emission measurements

The tests shall be performed and documented according the following given in Table 2-10.

Test MDI test network (BIN)

Type of measuring on MDI pins

Coupling resistors

Sample

R1

[]

R2

[]

E1

standard

symmetric 120 120

Set of 2 samples of each group (best case /

typical / worst case)

E2 + 2.5 % unbalanced 121 118

E3 - 2.5 % unbalanced 118 121

E4

optimized

symmetric 120 120

E5 + 2.5 % unbalanced 121 118

E6 - 2.5 % unbalanced 118 121

Table 2-10: Required emission measurements

For each test case a diagram has to be presented in the test report. Recommended limits are given in

Appendix B.4.

OPEN Alliance


Appendix A - Test circuit boards

A.1 Example for test fixture S-Parameter measurement

The calibration points are the pads of the CMC at the test fixture board.

Figure A-1: Example Test fixture S-Parameter measurement - mixed mode, top layer

Figure A-2: Example Test fixture S-Parameter measurement - single ended, top layer

OPEN Alliance


Appendix B – Recommended limits for tests

B.1 S-Parameter measurements

For evaluation of mixed mode S-Parameters two limit classes for each parameter given in Figure B-1

through Figure B-4 are recommended. The limits are valid for test cases S1 through S8.

Figure B-1: Recommended limits for Sdd11 and Sdd22 (RL)

Figure B-2: Recommended limits for Sdd21 (IL)

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Limit

[dB]

[MHz]

S-Parameter measurement CMC for OA BroadRReach Item: RL (Sdd11,Sdd22)

f [MHz] RL [dB]

1 - 2710 - 2766 - 19

-5,0

-4,0

-3,0

-2,0

-1,0

0,0

1,0

1 10 100 1000

Limit

[dB]

[MHz]

S-Parameter measurement CMC for OA BroadRReach Item: IL (Sdd21)

f [MHz] IL [dB]

1 - 0,510 - 0,533 - 0,766 - 1,0

OPEN Alliance


Figure B-3: Recommended limits for Scc21 (CMR)

Figure B-4: Recommended limits for Ssd21, Ssd12 (DCMR) and Sds21, Sds12 (CDMR)

-60

-50

-40

-30

-20

-10

0

1 10 100 1000

Limit

[dB]

[MHz]

S-Parameter measurement CMC for OA BroadRReach Item: Common mode Rejection (Scc21)

f [MHz] CMR [dB]

1 - 2510 - 4580 - 45

1000 - 23

-100

-90

-80

-70

-60

-50

-40

-30

-20

-10

1 10 100 1000

Limit

[dB]

[MHz]

S-Parameter measurement CMC for OA BroadRReach Item: Common to Differential mode Rejection (Ssd21,Ssd12)

Differential to Common mode Rejection (Sds21,Sds12)

f [MHz] CDMR/DCMR[dB]

1 - 7010 - 70

100 - 50300 - 34

1000 - 24

OPEN Alliance


B.2 Damage from ESD

It is recommended that the CMC must withstand the ESD discharge with discharge voltage amplitude of

+/- 6 kV without damage.

B.3 Increase in RF immunity of interface network

For evaluation of the increase in RF immunity of interface network caused by the CMC two limit classes

given in Figure B-5 are recommended. The limits are valid for test cases D3, D4 and D5 (DPI tests on MDI

pins using optimized MDI test network).

Figure B-5: Recommended limits for DPI tests

10

15

20

25

30

35

40

1 10 100 1000

Limit

[MHz]

[dBm]

DPI Test - CMC for OA BroadRReach

f [MHz] DPI [dBm]

1 218 39

88 391000 33

OPEN Alliance


B.4 Decrease in RF emission of interface network

For evaluation of the decrease in RF emission of interface network caused by the CMC two limit classes

given in Figure B-6 are recommended. The limits are valid for test cases D3, D4 and D5 (150 Ohm emission

measurements on MDI pins using optimized MDI test network).

Figure B-6: Recommended limits for emission measurements

=== END OF DOCUMENT ===

-10

0

10

20

30

40

50

60

70

80

0,1 1 10 100 1000 10000

Limit

[MHz]

[dBµV]

150 Ohm Emission Measurement - CMC for OA BroadRReach

f [MHz] EMI [dBµV]

0,15 720,30 720,75 55

10 5576 23

2750 23

Documents

EMC Test Specification for BroadR-Reach® Common Mode …...Author & Company Dr. Bernd Körber, FTZ Zwickau Title EMC Test Specification for BroadR-Reach® Common Mode Chokes Version