1、 ECMA TR/93 1stEdition / December 2007 Measuring Emissions from Modules Ecma International Rue du Rhne 114 CH-1204 Geneva T/F: +41 22 849 6000/01 www.ecma-international.org IW TR-093.doc 02/01/2008 14:39:00 Measuring Emissions from Modules Technical Report ECMA TR/93 1stEdition / December 2007 . Int
2、roduction Manufacturers need to know how the insertion of add-on modules affects the compliance of their products with applicable EMC requirements. VCCI, an Ecma member, developed a method to determine the RF disturbances generated by a module into its power feeding leads. This Ecma Technical Report
3、 develops that measurement method. Conducted RF disturbances determined according to that method can be used as a measure of the contribution of an add-on module to the RF disturbances generated by the host appliance. The method may be used to compare various modules or to estimate the interference
4、potential of a specific module, but is not intended to be used to assess compliance with applicable national or international standards. This Ecma Technical Report has been adopted by the General Assembly of December 2007. - i - Table of contents 1 Scope 1 2 References 1 3 Definitions and abreviatio
5、ns 1 3.1 Definitions 1 3.1.1 Magnetic probe 1 3.1.2 Module 1 3.2 Abbreviations 1 4 Measuring facility 1 4.1 Shielded room 1 4.2 Fixture for magnetic probe 1 4.3 Measuring instruments 2 4.3.1 Measuring receiver 2 4.3.2 Spectrum analyzer 2 4.3.3 Magnetic probe 2 4.4 Test board 4 5 Measuring Method 4 5
6、.1 Temperature 4 5.2 Power supply 4 5.3 Positioning of MUT and magnetic probe 4 5.3.1 Positioning of MUT 4 5.3.2 Space and positioning of magnetic probe 4 5.4 Measurement procedure 5 5.5 Reporting measurement results 6 6 Method for calibrating the magnetic probe 7 6.1 Application 7 6.2 Measuring ins
7、truments used for calibrating the magnetic probe 7 6.2.1 Preamplifier 7 6.2.2 Micro-strip line 7 6.2.3 Other measuring instruments 7 6.3 Calibration procedures 7 Annex A Conditions for measuring emissions from the Module Under Test 9 A.1 Test board 9 - ii - A.1.1 Layer placement 9 A.1.2 Decoupling c
8、apacitor 10 A.1.3 Other components 10 A.1.4 Measuring circuit 10 A.2 Integrated memory 11 A.2.1 Placement of MUT 11 A.2.2 Operating conditions 11 A.3 Integrated disk unit 12 A.3.1 Placement of MUT 12 A.3.2 Operating conditions 12 A.4 Interface board 14 A.4.1 Placement of MUT 14 A.4.2 Operating condi
9、tions 14 Annex B Current measurements with a magnetic probe 17 Annex C Influence of magnetic-probe placement on measured values 19 - 1 - 1 Scope This Ecma Technical Report provides guidelines for measuring electromagnetic emissions from modules, in view of assessing the impact of such modules on emi
10、ssions from products which may incorporate them. The present guidelines cover measurement methods as well as measuring facilities. Detailed technical conditions for testing are separately stipulated in Annex A. Modules covered by this document, as well as the equipment incorporating them have a supp
11、ly voltage rating not exceeding 600 VDC. 2 References IEC 61967-1 (2002) Integrated circuits - Measurement of electromagnetic emissions, 150 kHz to 1 GHz - Part 1: General conditions and definitions IEC 61967-6 (2002) Integrated circuits - Measurement of electromagnetic emissions, 150 kHz to 1 GHz -
12、 Part 6: Measurement of conducted emissions - Magnetic probe method CISPR 16-1-1 (2003) Specification for radio disturbance and immunity measuring apparatus and methods 3 Definitions and abbreviations 3.1 Definitions 3.1.1 Magnetic probe Non-contact current probe using magnetic coupling 3.1.2 Module
13、 A printed circuit board or other assembly intended to be buit-in into a device 3.2 Abbreviations FR-4 Flame Resistant 4 MUT Module Under Test RBW Resolution Bandwidth SNR Signal to Noise Ratio 4 Measuring facility This document assumes that current measurements are made using the magnetic probe def
14、ined in IEC 61967-6. 4.1 Shielded room To obtain accurate results, measurements should be carried out in a shielded room, which can eliminate the emissions from surrounding environment. However, at locations where the measured emissions from the surrounding environment are lower than the ones define
15、d in 2) of 5.4, the shielded room need not be used. 4.2 Fixture for magnetic probe A special fixture may be needed to fix a magnetic probe accurately and stably over the micro-strip line on a test board. - 2 - 4.3 Measuring instruments To obtain accurate and repeatable results, measuring instruments
16、 should meet the conditions stated in CISPR 16-1-1 (2003). These instruments - for example, measuring receivers, spectrum analyzers, and cables are be periodically calibrated and checked, ideally once a year. The method used for calibration is either directly or indirectly traceable to national stan
17、dards. The procedure for calibrating the magnetic probe is described in Clause 6. 4.3.1 Measuring receiver Table 1 Settings of frequency range and bandwidth of the measuring receiver Frequency range 10 MHz 30 MHz 30 MHz 1 GHz 6 dB bandwidth 9 kHz 120 kHz For details about the settings of the measuri
18、ng receiver, refer to CISPR 16-1-1 (2003). 4.3.2 Spectrum analyzer Table 2 Settings of frequency range and RBW of the spectrum analyzer Frequency range 10 MHz 30 MHz 30 MHz 1 GHz 3 dB RBW 10 kHz 100 kHz 4.3.3 Magnetic probe The magnetic probe is constructed with a shield against static electricity.
19、The structure of the magnetic probe is shown in Figures 1 through 4. Figure 1 Magnetic probe Layer 1 and 3 1.8 mm 30 mm 0.8 mm Via : Inner diameter 0.25 mm0.2 mm10 mm 8.4 mm 0.1 mm 10 mm Center ViaVia- 3 - Figure 2 Magnetic probe Figure 3 Magnetic probe Layer 2 : Copper foil SMA connectorLayer 1 Lay
20、er 2 Layer 3 30 mm Via Via 10 mm 30 mm Via 0.1 mm 10 mm 4.6 mm1.0 mm Center Via Inner diameter 0.25 mm 0.4 mm - 4 - Figure 4 Magnetic probe structure of each layer 4.4 Test board To measure emissions from a module a test board has to be used to which the MUT is attached. A micro-strip line to measur
21、e with the magnetic probe shall be provided on the test board. For the details, consult Annex A. 5 Measuring Method 5.1 Temperature The ambient temperature of the actual test facility is within the range of 15 C to 35 C. The temperature during measurement is being recorded. 5.2 Power supply The powe
22、r supply feeds the MUT with the required voltage and current for that MUT. 5.3 Positioning of MUT and magnetic probe 5.3.1 Positioning of MUT The MUT is positioned on the top layer of the test board, as detailed in Annex A. 5.3.2 Spacing and positioning of magnetic probe The magnetic probe is positi
23、oned in such a manner that: - the space between the tip of the magnetic probe and the micro-strip line is 1.0 mm 0.1 mm; Layer 3 Layer 2Layer 1 InsulatorStructure of each layer layer 1 ： Thickness of copper foil 0.035 mmThickness of Insulator 0.2 mm layer 2 ： Thickness of copper foil 0.035 mmThickne
24、ss of Insulator 0.2 mm layer 3： Thickness of copper foil 0.035 mmInsulatorCenter Insulator ( glass epoxy ) - 5 - - the positioning angle of the magnetic probe to the micro-strip line is less than 5 degrees; - the magnetic probe is at the center of the longer dimension of the micro-strip line. More d
25、etails can be found in Annex C. 5.4 Measurement procedure Measurements shall be taken in the following steps: 1) Setup Figures 5 and 6 show the test setup and its general configuration. More details can be found in Annex A. Figure 5 Test setup Micro-strip line Space between micro-strip line and magn
26、etic probe tip 1.0 0.1 mm Magnetic probe Ground layer for micro-strip line (layer 2)C2 MUTLayer 1 Bottom layer Test board - 6 - Figure 6 Configuration of measuring facility 2) Measurement of ambient noise Ambient noise is measured with the MUT not connected to the test board, but with all other part
27、s of the test setup powered on. The measured levels should be 6 dB or more lower than the limits set for the MUT. 3) Measurement of MUT emission The MUT is connected to the test board and the emission is measured while the MUT is in operation. The recorded values should be the highest of the results
28、 of at least 10 consecutive measurements, made while the MUT is continuously operated. An attempt should be made to maximize the emission, in a way which is consistent with the typical applications of the MUT. More details can be found in Annex A. 4) Transformation of measured data to current When t
29、he measuring instrument does not provide a direct reading of the current in the micro-strip line under the probe, that current can be calculated using formula: I = Vp + Cf Ch dB(A) Where: I is RF current, in dB(A). Vp is the output voltage of the magnetic probe, in dB(V). Cf is the calibration facto
30、r of the magnetic probe, in dB(A/m/V). Ch is the coupling factor of the test board, in dB(1/m). More details about current measurements with a magnetic probe can be found in Annex A.1. 5.5 Reporting measurement results The test report should indicate at least the six highest emission values recorded
31、 according to 5.4 point 3), together with the frequencies at which they have been recorded. The test report should also document the test configuration to allow accurate repetition of the test. Spectrum analyzer MUT Magnetic probe Preamplifier Cable Test board for MUT - 7 - 6 Method for calibrating
32、the magnetic probe 6.1 Application Annex B describes the procedure to calibrate the magnetic probe by using a micro-strip line as an electromagnetic-wave generator. The following IEC documents are used as reference for the calibration of the magnetic probe: - IEC 61967-1 (2002 - IEC 61967-6 (2002).
33、Other instruments should be calibrated based on CISPR 16-1-1 (2003) describing the calibration method for a shielded-loop type magnetic probe. 6.2 Measuring instruments used for calibrating the magnetic probe 6.2.1 Preamplifier A preamplifier may be used to obtain a sufficient SNR. 6.2.2 Micro-strip
34、 line A micro-strip line structure such as that shown in Figure 7 should be used as reference signal source. The insulator thickness (h) of the board that composes the micro-strip line should be 0.6 mm, and the characteristic impedance should be 50 5 . When FR-4 is used for the board (dielectric con
35、stant r = 4.7), the strip conductor width (W) should be 1.0 mm, and the ground plane width (Wg) of the micro-strip line should be at least 50 mm. The micro-strip line as structured above should be long enough (100 mm or more is recommended), and should have a sufficient high frequency performance. C
36、alibration should be performed at a power level sufficient to obtain at least 6 dB SNR over the frequency range in which the measurement will be made. Figure 7 Cross-sectional view of a micro-strip line for calibration 6.2.3 Other measuring instruments Signal generator, spectrum analyzer, and other
37、measuring instruments should be calibrated according to their respective applicable procedure. 6.3 Calibration procedures 1) The gain or loss of the test setup should be measured. When a preamplifier is used, it should be included in this measurement. 2) As an example, a setup of the magnetic probe
38、calibration is shown in Figure 8. The magnetic probe is placed over the micro-strip lines in such a way that the plane of the loop is perpendicular to the ground plane and parallel to the longitudinal axis of the micro-strip line. The center of the probe is located within 0.4 mm (horizontal displace
39、ment) from the center of the micro-strip line. The face angle of the probe is within a 5 deviation from the axis of the micro-strip line, in order to keep the deviation within 0.2 dB (Refer to Annex C. Influence of W (1.0 mm) h (0.6 mm) Wg (50 mm or more) Strip line Ground Insulator ( r=4.7) - 8 - m
40、agnetic-probe placement on measured values). The distance from the micro-strip line surface to the probe tip is maintained within 1.0 mm 0.1 mm. These restrictions on the probe placement are maintained to obtain calibration factors as accurately as possible. The maximum error for calibration factors
41、 under these restrictions is estimated to be less than 1.6 dB. The accuracy of the calibration factors for the probe with the dimensions specified in 5.4.3 of the Technical Requirements is regarded as better than 1.0 dB. Further information about the influence of the placement factors on the measure
42、d values is given in Annex C. Influence of magnetic-probe placement on measured values. 3) A signal generator is connected to one end of the micro-strip line, and a 50 terminator to the other end. Also, the cable is connected from the magnetic probe connector to a spectrum analyzer as shown in Figur
43、e 8. 4) Using the signal generator, the reference micro-strip line is excited at frequencies recommended below, and the level of the RF signal induced in the magnetic probe is measured by the spectrum analyzer. Frequencies of 10, 20, 40, 60, 80, 100, 200, 400, 600, 800, and 1000 MHz are recommended.
44、 5) The calibration factor is calculated by the following equation: h Cf = 20log Vp + Vs 30 (1) Y(Y + 2h) where Cf is the calibration factor for the magnetic field dB(A/m/V). Y is the distance between the strip conductor and the center of the loop of the magnetic probe (m). h is the insulator thickn
45、ess of the micro-strip board used for calibration (m). Vp is the output voltage of the magnetic probe dB(V). Vs is the output voltage of the signal generator dB(V). Figure 8 Setup for probe calibration 1 mm50Terminator Spectrum analyzer Signal generator Magnetic probe Micro-strip line SMA or APC 3.5
46、 mm - 9 - Annex A Conditions for measuring emissions from the Module Under Test This Annex supplements Clause 6. It includes the placement and the operating conditions of the module as a MUT to obtain a higher repeatability of the measurement. The test board consists of a control circuit and a power
47、 supply; it is required to operate the MUT as a single unit; the printed circuit feeding the MUT contains a micro-strip line for measuring the current to the MUT with a magnetic probe. A.1 Test board A.1.1 Layer placement The test board should have a multi-layer structure composed of four layers or
48、more. Additional layers may be inserted between the bottom layer and the ground plane to accommodate additional signal and/or power routing, as required. 1) Layer 1 The MUT shall be put on layer 1. The power supply line for measurement and the peripheral ground planes shall be placed on this plane.
49、With this power supply line pattern, each power line shall be constructed in accordance with Figure A.1. The regular width of the power supply line will be 1.0 mm to achieve a high spatial resolution. If the regular line width lacks current capacity, you can change the line width of the micro-strip line. For details, refer to Annex B. The length of the power supply line (in Figure A.1, the distance from the center of the via to VDDland to the 0.1 F decoupling capacitor) shall be a maximum of 25 mm to avoid standi
