Electromagnetic Interference (EMI) is always a potential problem with switched-mode power supplies, both AC-DC and DC-DC converters. Modern designs can perform well for emissions and immunity but external connections must still be correct for the best performance. Sometimes, extra filtering is necessary to meet specific application requirements. However, incorrect filter … [Read more...]
Standards
EMI Filtering 101: Understanding the Basics
Introduction To start at the very beginning, what is an electrical filter? An electrical filter can be passive, active, analog, or digital. It is a device usually composed of discrete components which can be placed between circuits, networks, or equipment/systems to either emphasize, de-emphasize or control the frequency components of a desired or undesired signal. The term … [Read more...]
5 Steps to Selecting the Right RF Power Amplifier
Introduction You need an RF power amplifier. You have measured the power of your signal and it is not enough. You may even have decided on a power level in Watts that you think will meet your needs. Are you ready to shop for an amplifier of that wattage? With so many variations in price, size, and efficiency for amplifiers that are all rated at the same number of Watts, many … [Read more...]
IEC-61000-4-3:2020 4th Edition Containing Multiple Signal Test Option Has Been Published
The new IEC 61000-4-3:2020 4th edition includes the following updates: a description of how to test using multiple test signals; the addition of information regarding EUT and cable layout; the removal of the upper-frequency limitation to take into account new services; and the further specification of how to characterize the uniform field area, as well as added clarification … [Read more...]
Review of Induced Signal Susceptibility Testing—DO-160 Section 19
The Issue Induced signal susceptibility has been a factor in electronic equipment performance since the dawning of voltage and current. Often referred to as crosstalk, the undesired coupling of one circuit’s signals to another may result in interference that degrades the integrity of either signal. This article examines the testing process prescribed by RTCA DO-160 Section … [Read more...]
The Emerging Threat of Tactical Electromagnetic Interference & Its Spread into Non-Defense Sectors
During the last five years intentional electromagnetic interference (IEMI) has emerged as a credible and increasingly likely threat to commercial and defence facilities alike, with a potentially crippling cost to individual organizations of such a localized attack. Hollywood has long used electromagnetic interference (EMI) and electromagnetic pulse (EMP) phenomena as the de … [Read more...]
Review of MIL-STD-1275 Requirements
Introduction This may seem disassociated from the electromagnetic compatibility (EMC) theme of this publication but issues dealing with power quality and the qualification testing has a direct link to EMC. Frequently the EMC engineers and technicians are tasked taking care of the power quality, so I believe that reviews of these standards are appropriate. MIL-STD-1275 deals … [Read more...]
New and Proposed Changes to CISPR SC I Standards
Are you familiar with CISPR 32 and CISPR 35? CISPR 32 was originally published in 2012, followed by a pair of corrigenda and then the 2nd edition was published in 2015. CISPR 32 replaced CISPR 13 (Broadcast receivers emissions) and CISPR 22 (ITE emissions), both of which were withdrawn by the IEC on March 5, 2017. In the EU CISPR 32 is published as EN 55032 and it has … [Read more...]
Review of MIL-STD-461 CS103 Intermodulation, CS104 Rejection of Undesired Signals and CS105 Cross-Modulation
Introduction Rapid technology advances in the wireless communications world make test and evaluation of Radio Frequency (RF) devices a difficult subject. It seems that by the time a new device hits the market, it has been made obsolete by the next generation. I recall hearing from a major electronics manufacturer CEO that 90% of sales happen within 90-days of market release … [Read more...]
Review of MIL-STD-461 CS117 Lightning Induced Transients, Cables and Power Leads
Introduction Lightning may produce a spectacular display when viewed, but the associated electromagnetic effects (EME) has the potential (pun intended) to severely damage electrical and electronic circuits. MIL-STD-461G added a new test method to evaluate device tolerance for induced current on equipment cables or insulation breakdown from the effects of indirect lightning. … [Read more...]
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