Introduction:

Integrated Circuits (ICs), while operating, can emit undesired electromagnetic energy through radiated emission (via air) and conducted emission (unwanted RF noise current flow through connected PCB traces, wires, or cables). This emitted electromagnetic energy from an IC may affect the performance/interfere with the operation of nearby devices; this phenomenon is referred to as electromagnetic interference (EMI).

Measurement of radiated and conducted emissions from an IC can offer valuable information for enhancing an IC's functionality and EMC performance.

Understanding IEC 61967-8:IEC 61967-8 is an EMC standard that deals with the Measurement of Radiated Emission from Integrated circuits (IC) by using the IC stripline method. It is the 8^th part of the IEC 61967 series. Currently, the second edition of this standard (IEC 61967-8:2023, published in 2023) is available and valid. The title of the standard is “Integrated circuits - Measurement of electromagnetic emissions - Part 8: Measurement of radiated emissions - IC stripline method”. The second edition cancels and supersedes the first edition, published in 2011.

The IEC 61967-8 document describes a method for measuring the electromagnetic radiated emission from an integrated circuit (IC) using an IC stripline.  In the IC stripline method, the IC under test is mounted on an EMC test board (PCB) between the active conductor and the IC stripline arrangement's ground plane (see Figure 1). The purpose of this test method is to provide a quantitative measure of the RF emissions from ICs for comparison or other evaluation. The document of this standard also specifies test conditions, test equipment, test set-up, test report requirements, and other content related to this measurement method. 

 The second edition (IEC 61967-8:2023) includes the following significant technical changes as compared to the previous edition:

• 150 kHz to 3 GHz frequency range was deleted from the scope.
• In this document, the extension of the upper usable frequency to 6 GHz or higher as long as the defined requirements are fulfilled.

Measurement test procedure, test set-up, and other details of IEC 61967-8:

As per the IEC 61967-8 standard, an IC stripline test configuration is used to measure the radiated emission of ICs. The stripline test setup is shown in the figure; here, the IC under test is mounted on an EMC test board (PCB) and is located between the active conductor and the IC stripline arrangement’s ground plane.  Also, one of the 50 Ω ports is terminated with a 50 Ω load. The remaining 50 Ω port is connected to the spectrum analyzer through the optional preamplifier.

The IC stripline test method is based on the TEM waveguide measurement principle according to the IEC 61000-4-20.  The IC stripline arrangement guides wave propagation in the transverse electromagnetic mode to produce a specific field for testing purposes between the active conductor and the enlarged ground plane, which is preferably the ground plane of a standard EMC test board as per the IEC 61967-1. There will be RF voltage at the stripline port, which is related to the electromagnetic radiation potential of the IC. This RF voltage will be measured using a spectrum analyzer or a measuring receiver. 

Four separate emissions measurements are taken in this test method. The first measurement is performed with the EMC test board mounted in an arbitrary orientation in the test setup. The second measurement is performed with the EMC test board rotated 90 degrees from the orientation in the first measurement. For each of the third and fourth measurements, again, the EMC test board is rotated to ensure emissions are measured from all four possible orientations. These four sets of measurement data shall be documented in the test report.

The EMC test board/IC test board controls the geometry and orientation of the operating IC relative to the IC stripline. This test board also eliminates any connecting leads within the IC stripline (these are on the backside of the board, which is opposite to the IC stripline). An optional shielding enclosure may be utilized for fixing the IC stripline configuration and for shielding purposes. This forms a closed version of the IC stripline. The closed version is opposite to the open version, which does not have a shielding enclosure.

IEC 61967-8:2023 document details: