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EMI is broadly defined as any unwanted electrical or electromagnetic energy that causes undesirable responses, degraded performance or failure in electronic equipment. Radio Frequency Interference (RFI) is a slightly more specific term often used interchangeably to describe the phenomenon. A filtered connector is widely recognized as the most effective point to filter noise either entering or exiting an EMI enclosure. Noise induced on a signal line within the box can be stripped off as it passes through the shielding enclosure, preventing radiation to adjacent equipment. Filtered connectors are also used to provide system immunity from external noise sources. Filters integrated into electronic connectors to achieve a reduction in conducted EMI have evolved over the years using a variety of elements and materials to achieve varying degrees of noise suppression. These filters are broadly identified as low-pass filters. A low-pass filter allows lower frequencies to pass through the filter with minimal reduction in signal strength, while attenuating signals with higher frequency. A filter element achieves this by essentially becoming a variable resistor connected between the signal lines and ground. The resistive value is inversely proportional to the frequency of the signal it is conducting. As the frequency increases, the resistance of the filter decreases, providing a lower impedance path to ground. The capacitors strip off the interfering noise from the signal as it passes through the filter device whilst diodes are used to clamp the voltage below a certain value, thereby protecting the electronic circuitry.
Filters can selectively attenuate specific frequency bands by introducing controlled impedance mismatches into the line. A low-pass filter effectively strips higher frequencies to ground while allowing desirable lower frequencies to pass through the filter. Filtered connectors are typically bi-directional, in that they can attenuate noise originating from either side of the filter, an important advantage when considering immunity.
Many different configurations of filters have been developed to address a variety of circuit requirements. The simplest design is the C or feed-through filter which consists of a single capacitor inserted between the signal line and ground. As the conducted signal frequency increases, the effective resistance of the capacitor decreases, and therefore shunting higher frequencies to ground. The result is a filter that passes lower frequencies while attenuating higher frequencies.... more
Filtered d type connectors are available as solder bucket and straight or right angled PCB, in standard, high density and dual-port configurations.
Filtered, mixed layout d connectors are ideal for power line filtering. Their small size means that they can be installed directly onto the backplane, backpanel, or power supply cable. These connectors and Adaptors are UL and CSA approved.
Because of the wide range of configurations available (including waterproof IP 67), these connectors are built to order.
 Download Filtered d-sub Data Sheet
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R max 10m 
