A VLSI for deskewing and fault tolerance in LVDS links

The device presented at this work is a switch implemented in a 0.35 mum CMOS process for compensating the skew which affects parallel data signal transmissions and for providing fault tolerance in large scale scalable systems, for instance used in trigger farms for high energy physics experiments. The SWIFT chip (SWItch for Fault Tolerance) is part of a cluster built around commercially components which has been inspired by the LHCb experiment. The skew is extremely important because it directly affects the sample window available to the receiver logic and either forces to use quality and expensive cables in order to minimize its effects or reduces the maximum signal transmission range or distance. This problem is handled by the deskewing circuitry at the SWIFT chip, which is able to match dynamically the signal transitions at the receiver link by adding an individual delay to each input signal in steps of 100 ps for LVDS signals up to 250 MHz. The deskew module is based on full custom analog delay units plus a digital skew detector block. A 16-bit processor is implemented for processing tasks. The chip compensates dynamically skews of LVDS signals up to 250 MHz in steps of 100 ps and adds fault tolerance to the farm of PCs by allowing the bypassing of a failing compute node to which is attached