Circuits for efficient detection of vector signaling codes for chip-to-chip communication
First Claim
1. A method comprising:
- receiving a set of input signals via a corresponding set of wires of a multi-wire bus;
generating a differential output signal on a pair of differential output nodes using, in a first mode of operation, a set of input transistors driven by the set of input signals, the set of input transistors connected to the pair of differential output nodes for driving a combined differential current through the pair of differential output nodes, the set of input transistors connected to the corresponding set of wires according to an input permutation selected from plurality of input permutations associated with a vector signaling code;
generating, in a second mode of operation, the differential output signal using a pair of input transistors connected to a first pair of wires of the multi-wire bus, the pair of input transistors receiving a first pair of input signals of the sset of input signals via the first pair of wires of the multi-wire bus and responsively driving a differential current through the pair of differential output nodes; and
providing the differential output signal for use in determining an output bit.
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Abstract
In a detection circuit, inputs correspond to received indications of vector signaling code words received by a first integrated circuit from a second integrated circuit. With four inputs, the circuit compares a first pair to obtain a first difference result and compares a second pair, disjoint from the first pair, to obtain a second difference result. The first and second difference results are then summed to form an output function. A system might use a plurality of such detection circuits to arrive at an input word. The circuit can include amplification, equalization, and input selection with efficient code word detection. The vector signaling code can be a Hadamard matrix code encoding for three input bits. The circuit might also have frequency-dependent gain, a selection function that directs one of the summation function result or the first difference result to the output function, variable gain, and/or a slicer.
449 Citations
20 Claims
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1. A method comprising:
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receiving a set of input signals via a corresponding set of wires of a multi-wire bus; generating a differential output signal on a pair of differential output nodes using, in a first mode of operation, a set of input transistors driven by the set of input signals, the set of input transistors connected to the pair of differential output nodes for driving a combined differential current through the pair of differential output nodes, the set of input transistors connected to the corresponding set of wires according to an input permutation selected from plurality of input permutations associated with a vector signaling code; generating, in a second mode of operation, the differential output signal using a pair of input transistors connected to a first pair of wires of the multi-wire bus, the pair of input transistors receiving a first pair of input signals of the sset of input signals via the first pair of wires of the multi-wire bus and responsively driving a differential current through the pair of differential output nodes; and providing the differential output signal for use in determining an output bit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. An apparatus comprising:
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a set of input transistors configured to receive a set of input signals via a corresponding set of wires of a multi-wire bus and to responsively generate a differential output signal on a pair of differential output nodes, the set of input transistors configured to; generate, in a first mode of operation, the differential output signal by driving a combined differential current through the pair of differential output nodes, the set of input transistors connected to the corresponding set of wires according to an input permutation selected from plurality of input permutations associated with a vector signaling code; and generate, in a second mode of operation, the differential output signal by driving a differential current through a pair of the set of input transistors according to a first pair of input signals of the set of input signals received via a first pair of wires of the multi-wire bus; and the pair of differential output nodes configured to provide the differential output signal for use in determining an output bit. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification