While operating, the Integrated circuits (ICs) may emit unwanted electromagnetic energy in the form of radiation (i.e., via air) as well as conduction (i.e., unwanted noise current flow via the PCB trace/wire). The unwanted electromagnetic energy emission from an IC may cause interference with nearby devices; this is called electromagnetic interference (EMI). 

Near-field scan techniques measure near-fields radiated by integrated circuits and their surrounding environment. The near-field scan method/technique utilizes near-field probes to measure the near electric, magnetic, or electromagnetic field components near or at the surface of an integrated circuit (IC). The probes used in the measurement procedure include an electric (E) field probe, a magnetic (H) field probe, and a combined electric and magnetic (E/H) field probe. The near-field scanning method/technique helps to identify the areas of radiation that may cause interference to nearby devices. The ability to identify a particular area of electric, magnetic, or electromagnetic field emission on a device can provide valuable information for the improvement of an IC both in terms of functionality and EMC performance.

In recent years, near-field scan techniques have evolved considerably. The near-field scan techniques use near-field probes with Probe-positioning, data acquisition systems, and measuring equipment for scanning and measuring radiated emission over the surface of the IC.  The probes' improved sensitivity, bandwidth, and spatial resolution help to analyze integrated circuits operating in the gigahertz range. The ability to measure radiation both in the time and frequency domain allows not only analysis of fields generated by an IC but also fields generated by externally applied disturbances propagating through the device.

Understanding IEC 61967-3:

IEC 61967-3 is an EMC standard that deals with the Measurement of Radiated Emission from Integrated circuits (IC) by the surface scan method. It is the third part of the IEC 61967 series. Currently, the second edition of this standard (IEC 61967-3:2014, published in 2014) is available and valid. The title of the standard is “Integrated circuits - Measurement of electromagnetic emissions - Part 3: Measurement of radiated emissions - Surface scan method”. The second edition cancels and supersedes the first edition, published in 2005.

The IEC 61967-3 document specifies a test procedure to measure the near electric, magnetic, or electromagnetic field components radiated at or near the surface of an integrated circuit (IC). This radiated emission measurement procedure applies in the frequency range of 150 kHz to 6 GHz. This document also includes test conditions, test equipment, test set-up, test report presentation details, and other content related to the measurement of near-fields radiated by integrated circuits. The test conditions, test equipment, and test setup shall meet the requirements described in IEC 61967-1.

Figure 1: One-input RF measurement setup 

During the measurement, the near-field probe is used to detect the radiated fields at or near the surface of an IC.  The signal captured by the probe is then fed to a spectrum analyzer or EMI receiver for measurement (Figure 1). Sometimes a preamplifier may be used between the probe and the spectrum analyzer or EMI receiver to improve the measurement sensitivity. According to the IEC 61967-3 document, if a single probe is not able to cover the entire frequency range, the frequency range may be divided into sub-ranges. This allows the use of multiple probes, with each one specifically designed for an individual frequency sub-range.  A brief description of the probe(s) used in the measurement shall be included in the test report.

The provided diagnostic procedure/test procedure is intended for IC architectural analysis, such as floor planning and power distribution optimization. This test procedure can apply to measurements on an IC mounted on any circuit board that is accessible to the scanning probe. In some scenarios, it is useful to scan both the IC and its environment. The standardized test board defined in IEC 61967-1 should be used to compare surface scan emissions between different ICs. 

The measurement method in the IEC 61967-3 provides a mapping of the electric or magnetic near-field emissions over the IC. The resolution of the measurement is determined by the precision of the probe-positioning system and the capability of the measurement probe. The method or test procedure of this document is intended for use up to 6 GHz. It is possible to extend the upper limit of frequency with existing probe technology but is beyond the scope of this specification. Measurements may be carried out in the time domain or the frequency domain.

The second edition (IEC 61967-3:2014) includes the following significant technical changes as compared to the previous edition:

1. Removal of: – 9.4 Data analysis; 

Annex D – Analysing the data from near-field surface scanning.

1. Addition of: 

• Introduction 
• 9.4 Measurement data
• 9.5 Post-processing 9.6 Data exchange 

 Annex D – Coordinate systems 

1. Expansion of: 
   •  8.4 Test technique 

Additional information of IEC 61967-3:2014