The new interface combines signaling and low power technology Rambus described in a February 2007 paper with clocking techniques used in its existing XDR interface. The result is an interconnect that can deliver as much as 4.3 Gbits/s per link using as little as a quarter of the power today's interfaces would require.

The approach employs a very low swing differential signaling technique that uses signals close to ground with a 100 millivolt swing, about a tenth the swing of today's interfaces. Rambus first disclosed the technique in the 2007 paper, describing a 6 Gbit/second serdes transceiver that consumed just 2.2 milliwatts per gigabit per second in a 90-nanometer process.

The approach uses a slightly modified version of the FlexClocking technique used on the Rambus XDR interface, implemented on the Sony Playstation3. Like XDR, the mobile interface drives most of its complexity to the controller, keeping the DRAM design relatively simple.

Rambus will show at DesignCon two 40nm test chips mounted in a package-on-package arrangement with one acting as a receiver and the other as a transmitter. The device will deliver 4.3 Gbits/s at 3 milliwatts per Gbit/s.

By: DocMemory
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