Extend Your Testing Capabilities
- June 1, 2018
- Posted by: Dominique
- Category: EMC Power Amplifiers
While smartphones, wireless headphones and other devices make life easier in many ways, signals from devices can interfere with, or be susceptible to interference from, other electronic devices. These interferences can span in significance from minor disturbances to a complete failure. As the number of electronic devices grows, it becomes increasingly necessary to identify, measure, limit, and resolve these interferences. (Get our free whitepaper on power amplifiers.)
EMC standards and regulations were established for electrical and electronic devices by governments, military services, and private industry, to name a few, to ensure electrical and electronic devices are operationally safe for their users and that they will continue to perform their functions in the midst of a variety of natural and man-made disturbances and interference.
Today in many countries electronic devices cannot be sold without being tested. As a result, many companies are now including EMC testing into their product development processes.
Electromagnetic compatibility is the ability of an electrical electronic device or system to operate in an acceptable way in its electromagnetic environment, without itself producing disturbances of significance to anything in the electromagnetic environment. EMC testing can be separated in two broad categories: Emissions testing and immunity testing.
What is emissions testing?
Emissions testing is measuring the electromagnetic signals emitted by the tested equipment. These measurements are taken to see if the equipment exceeds permissible limits that potentially interfere with the performance of other devices, or could even present potentially hazardous conditions to human health and well-being.
What is immunity testing?
Immunity testing is conducted for the purposes of determining whether the tested equipment can function properly when exposed to defined levels of radio frequency energy and waveforms.
Failure of devices can result in accidents leading to injuries and even death. As our reliance on electronic devices continuously increases, efficient and effective EMC testing is all the more essential.
Effective EMC Testing Requires Amplifiers
To test a device, you must subject it to defined levels of radiated radio frequency energy over a wide range of frequencies. Then you have to verify that the device still works properly, or that it doesn’t. Testing normally requires a very high electric field strength measured in Volts/meter that can only be provided by amplifiers, which are composed of active components which multiply an input signal without corrupting it.
The majority of EMC amplifiers use solid state RF transistors, which are organized into “classes of operation,” based on how they operate in different conditions; this varies by transistor type. Classes of operation are defined in terms of the amplifier’s “conduction angle.”
- Class A amplifiers have a conduction angle of 360°, meaning that the transistor conducts over the entire input waveform cycle, or 100% of the input cycle.
- Class B amplifiers have a conduction angle of 180° means that the amplifier conducts over only half of the waveform input cycle. These are is not suitable for EMC testing because they are very sensitive to mismatched loads.
A compromise exists with the AB Class, which has a conduction angle between 180° and 360°. Other classes exist but they are not normally pertinent to the discussion of EMC amplifiers. To learn more about types of Power Amplifiers and which best suit your testing environment, download our free whitepaper, complete with test setup examples.