Types of EMI suppression filters for audiovisual systems

The placement of EMI suppression filters for audiovisual systems has become an unavoidable and urgent requirement when designing the installation or professional integration of audiovisual equipment. In the process, technicians must perform the necessary tests to ensure that EMI mitigation solutions are applied to attenuate or weaken unwanted signals radiating inside or outside a device without negatively affecting its performance.

In this regard, and depending on the EMI mitigation technology that is decided upon, design changes to a particular device or complete redesigns of the integration scheme may be required for them to function properly. However, EMI mitigation technologies in general will require the simple addition or replacement of a component, such as a power input or filter, to provide the necessary interruption of unwanted signals.

Introduction to EMI filters in audiovisual signals

EMI suppression filters for audiovisual systems and for other uses, they help reduce emissions from a device when properly installed. EMC/EMI problems are often unique to a product, and particular signals can spread across the frequency spectrum and at a variety of power levels. In addition, it may be necessary to filter the different terminals of the device that carry DC, AC, data signals, or power control signals. Therefore, there are several different types of EMC/EMI filters to account for the ranges of EMC/EMI issues.

Types of EMI suppression filters for audiovisual systems

Typical types of EMI filters are designed for a specific type of signal and the devices in which they will be installed. The wide variety of devices and equipment that benefit from EMI filtering requires a range of standard solutions, as well as a high degree of customisation, so it will be up to the technician to determine the appropriate ones. EMI suppression filters for audiovisual systems. The following are some common types of EMI filters.

PCB filters

PCB filters are EMI filters that are specifically designed to be compact, cost-effective EMI/RFI filtering solutions that can be mounted on a PCB with standard through-hole soldering.

Power input modules / IEC input filters

IEC input filters are power input modules that are essentially single-phase filters integrated into standard IEC inputs and power input modules. These types of filters are very useful for solving EMI problems and passing EMC tests in a short period of time, especially with portable electrical equipment, domestic equipment, medical equipment, test and measurement equipment, and rack-mounted equipment for 250 volts AC. These types of filters typically provide high conducted attenuation from 10 kHz to 30 MHz, but they also provide attenuation below 10 kHz and above 30 MHz.

Single-stage filters

A single-phase EMI filter is designed for AC or DC lines with a positive and negative, or dual, signal/power path. This type of filter is installed in line with the power/signal lines, allowing DC and AC signals to pass without attenuation, while strongly attenuating signals from 10 kHz to 30 MHz. These types of filters are used in single-phase motors, power supplies, office equipment, and test and measurement equipment, among other applications. Some single-phase filters are optimised for specific applications, such as DC performance, medical equipment requirements, industrial safety requirements, and other standards.

As some standards require much greater EMI/RFI mitigation, there are varying degrees of complexity for single-phase, single-stage, two-stage, and multi-stage filters. Essentially, additional stages improve a filter's attenuation and signal blocking capabilities, which can mean greater attenuation in a given frequency band or greater attenuation across a broader spectrum of frequencies, depending on the design.

Three-phase filters

Three-phase filters are similar to single-phase filters, except that the filter is designed to filter all three signal/power lines for three-phase power and motor systems. There are some three-phase filters that also include neutral line filtering for applications that require it. Three-phase filters are useful as mains input filters for industrial equipment, tools, machinery, and automation systems. Depending on a filter's leakage performance, they can even be used with some medical devices and equipment such as those used in audiovisual integration of operating theatres.

DC filters

DC filters are specifically designed to filter DC power supplies and control signal lines. This could be to protect solar panels, photovoltaic charging/conversion systems, battery charging and conditioning systems, DC motor drives, and inverters/converters. Although similar to AC EMI filters, DC EMI filters are optimised to pass only DC signals and are typically rated for higher DC voltages and currents. These filters are useful for preventing premature ageing and protecting solar panels from conducted emissions such as HF leakage and leakage currents.

Power filters

Power filters are designed as in-line filters, which can provide increasing attenuation up to 1 GHz and beyond. These types of filters are often used to protect sensitive equipment within shielded enclosures, such as a power line filter, line shielding for high-performance computing applications, and more. Power filters typically provide greater EMI/RFI suppression than power capacitors, especially where source impedances are less than 50 ohms.

So far, we have looked at the different types of EMI filters and their various uses. However, not all noise suppression technologies include EMI filters. With this in mind, we invite you to learn about all the technologies for mitigating the EMI effect on audiovisual signals applied to the audiovisual integration solutions for operating theatres, recently published on our blog.

Finally, it can be stated that EMC/EMI mitigation and suppression technologies are essential for designing the professional installation or integration of audiovisual equipment and complying with rigorous standards and regulations. In this regard, the EMI suppression filters for audiovisual systems, are a versatile and effective solution for a wide range of applications, and can be easily customised to meet specific EMI suppression requirements. However, there are many factors to consider when selecting an ideal EMI suppression solution, so leveraging the expertise of EMC/EMI filter experts can help speed up and optimise the selection and integration process.

If you would like more information about the use of EMI suppression filters for audiovisual systems, as well as trends in the integration of audiovisual systems in operating theatres and hospitals, we invite you to subscribe to our Newsletter, a newsletter that will provide you with technical content on new automation technologies for companies in various sectors.