Pmc-sierra, Inc.

Pmc-sierra Us, Inc.

Nicholas Wayne Rolheiser

Winston Ki-Cheong Mok

Carl Dietz McCrosky

Scott Arthur Muma

Andrew Milton Hughes

A method and an apparatus for reducing power consumption and digital logic noise in a time division multiplexed memory switch. The method is embodied in an egress selection switch (ESS) block architecture. The ESS block includes a data disable block which prevents the propagation of data, in particular ingress grains, to a given group of egress ports if the data is not selected by any of the egress ports in a given group. While the ingress data disable method partitions ports into groups and saves power by disabling the fanout tree from the root on a port group basis, the egress data disable method saves power on a port group basis by disabling the fanout tree from the tail end in addition to applying the ingress data disable method. The ESS block also includes an grain select block for selecting and storing a given ingress grain for eventual output to an egress port.

Egress selection switch architecture with power management

A method and apparatus are provided for reducing current demand variations in large fanout trees. The fanout tree is split into at least 2 sub-groups, each preferably with substantially equal parasitic capacitance. Data is then scrambled according to a scrambling sequence function to provide scrambled data having a constant number of bits that are toggled with respect to time, such as when observed in pairs of sub-groups. Functionally, an apparatus according to an embodiment of the present invention includes 3 blocks: a scrambler, egress logic, and a de-scrambler. The egress logic is simply a block of storage that can reorder the bytes received from the scrambler. The de-scrambler de-scrambles the retransmitted data based on the scrambling sequence function. Embodiments of the present invention can be applied to any system where data must fanout from a single source to many destinations, such as switches.

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Saskatoon, Canada

Nicholas Wayne Rolheiser