IEC 61967-5:2003 pdf – Integrated circuits – Measurement of electromagnetic emissions, 150 kHz to 1 GHz – Part 5: Measurement of conducted emissions – Workbench Faraday Cage method.
1 Scope This part of IEC 61967 describes a method to measure the conducted electromagnetic emission of integrated circuits either applied on the standardised test-board or on a final printed circuit board (PCB). Furthermore, this standard defines measures to maintain uniform requirements, describes the measurement method and gives guidance for the Workbench Faraday Cage measurement method. As the measurements take place on a table with the usage of a small Faraday cage, this method is called the Workbench Faraday Cage method or the Workbench method. The method has a high repeatability and a good relationship to the measured RF emission of final applications with the integrated circuits used. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60050(131):2002, International Electrotechnical Vocabulary (IEV) – Part 131: Circuit theory IEC 60050(161):1990, International Electrotechnical Vocabulary (IEV) – Chapter 161: Electromagnetic compatibility IEC 61967-1:2002, Integrated circuits – Measurement of electromagnetic emissions, 150 kHz to 1 GHz – Part 1: General conditions and definitions IEC 61000-4-6:1996, Electromagnetic compatibility (EMC) – Part 4-6: Testing and measure- ment techniques – Immunity to conducted disturbances, induced by radio-frequency fields 3 Definitions For the purposes of this document, the definitions in IEC 61967-1, IEC 60050(131) and IEC 60050(161) apply. 4 General This part of IEC 61967 applies to integrated circuits (ICs) which can perform “stand-alone” functions when applied on a physically small printed circuit board (PCB).
The RF emission from these ICs can be measured under pre-defined conditions. In addition, the method allows measurements on PCBs that are equal to or closely related to realistic applications. This gives the user an indication of the expected emission once the IC(s) is used in an application. This method makes it possible to classify ICs for dedicated functions where EMC constraints are applicable. 4.1 Measurement philosophy The Workbench method is derived from IEC 61000-4-6; see Figure 1. The method described in IEC 61000-4-6 assumes that supply and signal cable(s) are attached to an electrically small PCB, with dimensions ≤ λ /2, i.e. 0,15 m at 1 GHz. The connected cables become the dominant antennas, so RF emission takes place via these “antennas”. The connected cables will have functions such as supply, communication and other signal interfaces and these cables are commonly not geometrically oriented in the same plane as the other cables. The antenna’s (common-mode) impedance per port has been normalised to 150 Ω with tolerances in the various frequency bands, see Annex B. By measuring either the voltage across or the current through these common-mode impedances, the RF emission is characterised. Direct radiation from the IC package can be small − see also IEC 61967-2 as an additional measurement method − and often negligible compared to the radiation caused by the cable(s) connected to the IC in its application. Because the supply and signal currents will flow through the reference layer(s) of the PCB, indirect coupling between the voltages and currents through the IC package and PCB are also established. Because of the concept chosen, the Workbench method shows the effect of the PCB layout, the IC supply decoupling, the RF performance of the used discrete components (capacitors, inductors) as well as the measures taken on the IC (e.g. on-chip decoupling, slope controlled output buffers, etc.).
4.2 Principle set-up The measurements take place above a metallic reference plane. With common-mode impedances defined, relations between measured voltage (current) and the RF emission and, in case of RF immunity testing, between local E/H fields and the applied disturbance voltage can be approximated. 4.3 Workbench concept With this Workbench method, a small Faraday cage is used. In principle, coupling and decoupling is similar to the method given in IEC 61000-4-6, but implemented by discrete resistors, connected to the several common-mode ports of the PCB, i.e. test board. The decoupling of supply and/or other I/O lines takes place via inductances built on ferrite cores, representing impedances >>150 Ω at the frequencies of interest, and feed-through filters installed through the wall of the cage. The Workbench basic set-up is shown in Figure 2. NOTE The decoupling impedance requirements, >>150 Ω, only have to be met at the frequency range of interest, when restricted. 5 Test conditions The test conditions shall be as described in IEC 61967-1. No special conditions apply, other than those mentioned in this clause. The Workbench method can be used for either absolute or comparative testing of ICs, either on the pre-defined, standardised, test board, as well as for the measurement of definitive applications including ICs. When measurements are carried out using a test board other than defined in IEC 61967-1, that PCB shall be described in such a way that repetition of the measurement remains possible. When necessary, a copy of the layout and circuit diagram shall be added to the test report.