Multi-level Decoder Skew Correction via Segmented Sampling

Solution Overview

Problem

In high-speed optical communication systems, the non-linear behavior of semiconductor lasers introduces skew and distortion in multi-level encoded signals, complicating the decoding process and affecting signal-to-noise ratio and bit error rate due to varying response speeds across different signal levels.

Innovation Solution

A data transmission system that employs multiple discrete decoding elements with adjusted sampling times to account for the skew introduced by the non-linear laser modulation, ensuring each level of the multi-level signal is sampled at its optimal time, using separate delay elements to compensate for the delays between signal levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple discrete decoding elements with adjusted sampling times are used to compensate for skew, then signal-to-noise ratio and bit error rate are improved, but device complexity increases

Engineering Contradiction:

Improvebit error rateVSAvoiddecoder complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The decoder is divided into multiple discrete decoding elements, each responsible for decoding a specific signal level. Each decoding element has its own sampling time adjustment mechanism, allowing independent optimization for each level while collectively handling the full PAM4 signal spectrum.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each decoding element is configured with specific local parameters including individual sampling times and reference levels tailored to its designated signal level. This local optimization allows each element to compensate for skew effects specific to its level without affecting other levels, improving overall reliability while maintaining manageable complexity through modular design.

Inventive Principle:

Principle #3Local quality

2Reliability

If multiple discrete decoding elements with adjusted sampling times are used to compensate for skew, then signal-to-noise ratio is improved, but device complexity increases

Engineering Contradiction:

Improvesignal-to-noise ratioVSAvoiddecoder complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The decoder is divided into multiple discrete decoding elements, each responsible for decoding a specific signal level. Each decoding element has its own sampling time adjustment mechanism, allowing independent optimization for each level while collectively handling the full PAM4 signal spectrum.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each decoding element is configured with specific local parameters including individual sampling times and reference levels tailored to its designated signal level. This local optimization allows each element to compensate for skew effects specific to its level without affecting other levels, improving overall reliability while maintaining manageable complexity through modular design.

Inventive Principle:

Principle #3Local quality

3Productivity

If non-linear laser modulation is used for PAM4 encoding, then data transmission rate is improved, but skew and distortion are introduced in the signal

Engineering Contradiction:

Improvedata transmission rateVSAvoidsignal skew and distortion

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent acknowledges that non-linear laser modulation inherently introduces skew and distortion, but converts this harmful effect into a manageable characteristic by pre-calculating and programming specific sampling time adjustments for each decoding element. The distortion pattern becomes predictable and compensable, allowing the system to maintain high data transmission rates while correcting the inevitable skew effects.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The sampling time adjustments for each decoding element are pre-calculated and programmed before operation. This preliminary configuration allows the system to anticipate and compensate for skew effects before they manifest as errors, enabling the system to fully utilize non-linear laser modulation for high-speed transmission while maintaining signal integrity through proactive correction.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9184841B2Multi-level decoder with skew correction

Publication Date: 2015.11.10 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

An optical communication system, a transmitter, a receiver, and methods of operating the same are provided. In particular, a transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The receiver is configured to provide skew correction to the optical signals received from the transmitter by dividing a received signal into separate level-specific components and sampling each of the components with distinct sampling blocks.