Picor Filters Attenuate Noise
in Chinese 3G and 4G Wireless Networks
Picor active filters (QPI series) are designed into the power systems of several large Chinese telecom OEMs that design TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) systems, a channel access method adopted by China for its own national wireless networks. TD-SCDMA is very similar to ATCA (Advanced Telecommunications Computing Architecture), in the regards to specifying such parameters as the power limit, EMI limits, and fault tolerance on a per board basis. Next generation (4G) networks achieve greater capacity through improved spectral efficiency.
Picor active filters are designed into multiple unique board TD-SCDMA designs, each using a different "industry standard" DC-DC converter. The mixed use of different converters typically makes the EMI and hot-swap design more challenging for passive designs. Picor active filters are universal in nature and are compatible with most industry standard converters and can therefore simplify the overall design effort. In TD-SCDMA systems each board typically has a requirement for hot-swap capability, a 48/12 V DC-DC converter and a need to achieve Class B EMI filtering. Power levels for TD-SCMA (3G) range anywhere from 70 to 150 W per board and the overall system has up to 40 boards per node. For 4G systems where more power may be needed, Picor QPI filters can support up to 14A in the same 25mm x 25mm SiP package size. Much like ATCA, the distributed power design of TD-SCDMA provides higher reliability, which comes however at the expense of PC board real estate. QPI models with integrated hot-swap save space from the filter perspective, and provide further space savings by integrating the hot-swap function. The QPI solutions can also address a broad range of other wireless telecom infrastructure platforms that are being adopted elsewhere around the world.
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