Common-mode signal: Difference between revisions

Revision as of 10:18, 7 May 2013

Revision as of 10:25, 7 May 2013

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* A ground differential between the transmitting and receiving locations.

Common-mode signals may be effectively eliminated by using [[differential amplifier]]s or receivers that respond only to voltage differences, ''e.g.,'' those between the wires that constitute a pair. They may be filtered using an inductor where a pair of signalling wires follow the same path through the inductor. Eg in a bifilar winding configuration, or as in the case of Ethernet, terminate in a transformer.<ref>http://ww2.pulseeng.com/products/datasheets/H325.pdf</ref>

High frequency common mode signals, for example, rf noise from a computing circuit, may be blocked using a ferrite bead clamped to the outside of a cable. These are often observable on laptop computer power supplies near the jack socket, and good quality mouse or printer USB cables and HDMI cables. <ref>http://www.elmac.co.uk/pdfs/ferrite.pdf</ref>

[[Switched-mode power supply|Switch mode power supplies]] include common and differential mode filtering inductors to block the switching signal noise returning into mains wiring.<ref>http://www.hottconsultants.com/pdf_files/APEC-2002.pdf</ref>

== See also ==

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==References==

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