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US 12,057,976 B2Granted
Vector signaling code with improved noise margin
AssigneeKandou Labs, S.A.
InventorsBrian Holden, Amin Shokrollahi
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Abstract
Methods are described allowing a vector signaling code to encode multi-level data without the significant alphabet size increase known to cause symbol dynamic range compression and thus increased noise susceptibility. By intentionally restricting the number of codewords used, good pin efficiency may be maintained along with improved system signal-to-noise ratio.
Claims20
A method comprising:
- receiving a plurality of codewords, each codeword sequentially received as a plurality of symbols in parallel over respective wires of a multi-wire channel, the symbols of each codeword having symbol values belonging to a constrained alphabet associated with a limited set of weighted summations of a plurality of mutually orthogonal sub-channel vectors according to a constrained set of pulse amplitude modulation (PAM)-M words, wherein M is an integer greater than two;
- generating, for each codeword, a PAM-M word from the constrained set of PAM-M words, each PAM-M word comprising a plurality of outputs generated by forming respective linear combinations of the plurality of symbols of the codeword according to respective sub-channel vectors of the plurality of mutually-orthogonal sub-channel vectors;
- and
- mapping each PAM-M word to a set of output signals.
1 more element
An apparatus comprising:
- a set of multi-input comparators (MICs) configured to receive a plurality of codewords, each codeword sequentially received as a plurality of symbols in parallel over respective wires of a multi-wire channel, the symbols of each codeword having symbol values belonging to a constrained alphabet associated with a limited set of weighted summations of a plurality of mutually orthogonal sub-channel vectors according to a constrained set of pulse amplitude modulation (PAM)-M words, wherein M is an integer greater than two;
- the MICs further configured to generate, for each codeword, a plurality of outputs of a PAM-M word from the constrained set of PAM-M words, each MIC configured to generate a respective output generated by forming a respective linear combination of the plurality of symbols of the codeword according to a respective sub-channel vectors of the plurality of mutually-orthogonal sub-channel vectors;
- and
- a decoder configured to map each PAM-M word to a set of output signals.
1 more element
Dependencies are inferred from the claim text.