Skew detection and correction for orthogonal differential vector signaling codes

Patent metadata

Field	Value
Publication number	US-10601574-B2
Application number	US-201916435404-A
Country	US
Kind code	B2
Filing date	Jun 7, 2019
Priority date	Jun 11, 2018
Publication date	Mar 24, 2020
Grant date	Mar 24, 2020

Abstract

Methods and systems are described for receiving a plurality of signals corresponding to symbols of a codeword on a plurality of wires of a multi-wire bus, and responsively generating a plurality of sub-channel outputs using a plurality of multi-input comparators (MICs) connected to the plurality of wires of the multi-wire bus, generating a plurality of wire-specific skew control signals, each wire-specific skew control signal of the plurality of wire-specific skew control signals generated by combining (i) one or more sub-channel specific skew measurement signals associated with corresponding sub-channel outputs undergoing a transition and (ii) a corresponding wire-specific transition delta, and providing the plurality of wire-specific skew control signals to respective wire-skew control elements to adjust wire-specific skew.

First claim

I claim:

1. A method comprising:
receiving a plurality of signals corresponding to symbols of a codeword on a plurality of wires of a multi-wire bus, and responsively generating a plurality of sub-channel outputs using a plurality of multi-input comparators (MICs) connected to the plurality of wires of the multi-wire bus;
generating a plurality of wire-specific skew control signals, each wire-specific skew control signal of the plurality of wire-specific skew control signals generated by combining (i) one or more sub-channel specific skew measurement signals associated with corresponding sub-channel outputs undergoing a transition and (ii) a corresponding wire-specific transition delta; and
providing the plurality of wire-specific skew control signals to respective wire-skew control elements to adjust wire-specific skew.

2. The method of claim 1 , wherein the corresponding wire-specific transition delta comprises a transition magnitude and transition direction.

3. The method of claim 1 , further comprising generating the corresponding wire-specific transition delta by:
generating a plurality of signals corresponding to recreated symbols of the received codeword and recreated symbols of a previously-received codeword; and
forming a difference between a signal corresponding to a recreated symbol of the received codeword and a signal corresponding to a recreated symbol of the previously-received codeword.

4. The method of claim 3 , wherein generating the plurality of signals corresponding to recreated symbols of the received codeword and the previously-received codeword comprises re-encoding corresponding sets of sub-channel outputs.

5. The method of claim 1 , wherein each sub-channel specific skew measurement signal comprises a corresponding early-late indication component obtained based on the corresponding sub-channel output.

6. The method of claim 1 , wherein each sub-channel specific skew measurement signal comprises a corresponding MIC input weighting coefficient component.

7. The method of claim 1 , wherein each wire-specific skew control signal of the plurality of wire-specific skew control signals is provided to a corresponding wire-skew adjustment circuit connected to a corresponding wire of the plurality of wires of the multi-wire bus.

8. The method of claim 7 , wherein each wire-skew adjustment circuit comprises a plurality of capacitive elements, and wherein each wire-specific skew control signal comprises a plurality of bits, each bit selectively coupling a corresponding capacitive element of the plurality of capacitive elements to the corresponding wire to adjust the wire-specific skew of the corresponding wire.

9. The method of claim 1 , further comprising identifying the sub-channel outputs undergoing a transition by identifying a transitional pattern over a sequence of sub-channel outputs including at least one previously-decoded sub-channel output.

10. The method of claim 1 , wherein the plurality of wire-specific skew control signals are provided to a transmitter circuit via a back channel to adjust signal transmission time of subsequent signals on the multi-wire bus.

11. An apparatus comprising:
a plurality of multi-input comparators (MICs) configured to receive a plurality of signals corresponding to symbols of a codeword on a plurality of wires of a multi-wire bus, and to responsively generate a plurality of sub-channel outputs;
a skew control circuit configured to generate a plurality of wire-specific skew control signals, each wire-specific skew control signal of the plurality of wire-specific skew control signals generated by combining (i) one or more sub-channel specific skew measurement signals associated with corresponding sub-channel outputs undergoing a transition and (ii) a corresponding wire-specific transition delta; and
a plurality of wire-skew control elements configured to receive the plurality of wire-specific skew control signals and to adjust wire-specific skew.

12. The apparatus of claim 11 , wherein the corresponding wire-specific transition delta comprises a transition magnitude and transition direction.

13. The apparatus of claim 11 , wherein the skew control circuit is configured to generate the corresponding wire-specific transition delta by:
generating a plurality of signals corresponding to recreated symbols of the received codeword and recreated symbols of a previously-received codeword; and
forming a difference between a signal corresponding to a recreated symbol of the received codeword and a signal corresponding to a recreated symbol of the previously-received codeword.

14. The apparatus of claim 11 , wherein the skew control circuit is configured to generate the corresponding wire-specific transition delta by comparing a previously-detected plurality of sub-channel outputs to the plurality of sub-channel outputs.

15. The apparatus of claim 11 , wherein each sub-channel specific skew measurement signal comprises a corresponding early-late indication component obtained based on the corresponding sub-channel output.

16. The apparatus of claim 11 , wherein each sub-channel specific skew measurement signal comprises a corresponding MIC input weighting coefficient component.

17. The apparatus of claim 11 , wherein the skew control circuit is configured to provide each wire-specific skew control signal of the plurality of wire-specific skew control signals to a corresponding wire-skew adjustment circuit connected to a corresponding wire of the plurality of wires of the multi-wire bus.

18. The apparatus of claim 17 , wherein each wire-skew adjustment circuit comprises a plurality of capacitive elements, and wherein each wire-specific skew control signal comprises a plurality of bits, each bit selectively coupling a corresponding capacitive element of the plurality of capacitive elements to the corresponding wire to adjust the wire-specific skew of the corresponding wire.

19. The apparatus of claim 11 , wherein the skew control circuit is configured to identify sub-channel outputs undergoing a transition by identifying a transitional pattern over a sequence of sub-channel outputs including at least one previously-decoded sub-channel output.

20. The apparatus of claim 11 , wherein the plurality of wire-skew control elements are in a set of drivers in a transmitter, and wherein the plurality of wire-specific skew control signals are conveyed to the transmitter via a back channel.

Assignees

• Kandou Labs SA

Inventors

• Hormati Ali

Classifications

• H04L25/0292 Primary

  Arrangements specific to the receiver end · CPC title

• H04L25/085

  Arrangements for reducing interference in line transmission systems, e.g. by differential transmission · CPC title

• H04L7/0087

  Preprocessing of received signal for synchronisation, e.g. by code conversion, pulse generation or edge detection · CPC title

• H03M7/20

  Conversion to or from n-out-of-m codes · CPC title

• H04L25/14

  Channel dividing arrangements {, i.e. in which a single bit stream is divided between several baseband channels and reassembled at the receiver} · CPC title