Serial Interconnect Lane Deskew via Transmitter Delay

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Solution Overview

Problem

Conventional high-speed serial data communication systems require additional circuitry for deskewing and realignment due to skewing issues, which increases complexity and cost.

Innovation Solution

Introducing predetermined delays in the transmission of serialized data groups across multiple serial links ensures that the first bit of each group arrives in order at the receiver, reducing the need for buffers and control logic by declaring a skew budget and dividing data into groups larger than the product of the number of lanes and skew in bit times.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If multiple high speed serial data paths are provided to increase effective data transfer rate, then productivity is improved, but device complexity increases due to skewing problems requiring additional buffers and control logic

Engineering Contradiction:

Improveeffective data transfer rateVSAvoidcomplexity of buffers and control logic

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The transmitter introduces predetermined delays into the transmission on various serial links before data transmission begins. By pre-calculating and applying delay values based on measured skew between lanes, the system ensures that data groups arrive at the receiver in the correct order without requiring complex deskewing circuitry. This preliminary action eliminates the need for buffers and control logic at the receiver side.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of allowing data to arrive out of order and then correcting the sequence at the receiver (conventional approach), the patent inverts the approach by pre-ordering the data transmission with predetermined delays applied at the transmitter. This ensures data arrives in the correct sequence from the start, eliminating the need for receiver-side deskewing operations.

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If data is divided into groups larger than M times S for transmission, then manufacturing precision is improved by ensuring correct arrival order, but loss of time increases due to grouping overhead

Engineering Contradiction:

Improvedata arrival order precisionVSAvoiddata transmission time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent changes the parameter of data group size to be specifically larger than M times S (where M is the number of lanes and S is the skew budget in bit times). This parameter adjustment ensures that even with maximum expected skew, the first bit of each data group will arrive in the correct order. The group size is optimized to balance precision requirements with transmission efficiency.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8259755B2Alignment and deskew for multiple lanes of serial interconnect

Publication Date: 2012.09.04 VELOCITY COMMUNICATION TECHNOLOGIES LLC

AI summary

Methods and apparatus are provided for data communication between a transmitter and receiver over a plurality of serial links, which cause the transmitter to send serialized groups of bits down each lane, in such a way that the first bit of each group (each lane) is guaranteed to arrive in the correct order at the receiving end. Various embodiments of the present invention include declaring a budget for the maximum skew between lanes. In such embodiments, subsequent to determining the skew budget between lanes, the data to be transmitted is divided into groups of N bits, where N is any convenient number larger than M times S, with M being the number of lanes and S being the budgeted skew, in bit times.