Multi-Level Modulation Signaling for Short Reach SERDES

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Solution Overview

Problem

Conventional high-speed SERDES circuits for short reach communications experience hyper-linear increases in power and area costs as data rates exceed 25 Gb/sec due to the use of 2-level non-return-to-zero (NRZ) signaling, leading to significant channel loss and complexity.

Innovation Solution

Implementing multi-level modulation signaling, such as 4-level pulse amplitude modulation (PAM), which reduces the signaling rate and subsequently decreases power and area requirements by encoding multiple bits per symbol, thereby reducing channel loss and simplifying receiver architecture.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If 2-level NRZ signaling is used for high-speed SERDES circuits, then data transmission capability is achieved, but power consumption and chip area increase hyper-linearly as data rates exceed 25 Gb/sec

Engineering Contradiction:
Improvedata rateVSAvoidpower consumption
Core Design Contradiction:
SpeedVSUse of energy by moving object

Solution Approach 1:

The patent changes the signaling parameter from 2-level NRZ to multi-level PAM (4-level, 8-level, or 16-level) modulation. This parameter change allows encoding multiple bits per symbol, reducing the required signaling rate for the same data rate, which in turn reduces power consumption and area requirements for high-speed SERDES circuits.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from binary signaling (2 levels) to multi-level signaling (4, 8, or 16 levels), adding dimensional complexity to the signal space. This allows more information to be transmitted per symbol, effectively reducing the signaling rate requirement and enabling high-speed communication with lower power and area costs.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Speed

If 2-level NRZ signaling is used for high-speed SERDES circuits, then data transmission capability is achieved, but chip area increases hyper-linearly as data rates exceed 25 Gb/sec

Engineering Contradiction:
Improvedata rateVSAvoidchip area
Core Design Contradiction:
SpeedVSArea of stationary object

Solution Approach 1:

The patent changes the signaling parameter from 2-level NRZ to multi-level PAM (4-level, 8-level, or 16-level) modulation. This parameter change allows encoding multiple bits per symbol, reducing the required signaling rate for the same data rate, which in turn reduces power consumption and area requirements for high-speed SERDES circuits.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent transitions from binary signaling (2 levels) to multi-level signaling (4, 8, or 16 levels), adding dimensional complexity to the signal space. This allows more information to be transmitted per symbol, effectively reducing the signaling rate requirement and enabling high-speed communication with lower power and area costs.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If multi-level modulation signaling is implemented, then signaling rate is reduced and power/area requirements decrease, but channel loss increases

Engineering Contradiction:
Improvepower consumptionVSAvoidchannel loss
Core Design Contradiction:
Use of energy by moving objectVSLoss of energy

Solution Approach 1:

The patent incorporates equalization circuitry that uses feedback mechanisms to compensate for channel loss. The equalizer processes the received signal to counteract attenuation and distortion introduced by the transmission channel, enabling reliable multi-level signaling despite increased channel loss.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent changes the signaling parameter from 2-level NRZ to multi-level PAM (4-level, 8-level, or 16-level) modulation. This parameter change allows encoding multiple bits per symbol, reducing the required signaling rate for the same data rate, which in turn reduces power consumption and area requirements for high-speed SERDES circuits.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentUS9338040B2Use of multi-level modulation signaling for short reach data communications
Publication Date: 2016.05.10 AVAGO TECHNOLOGIES INTERNATIONAL SALES PTE LTD

AI summary

A short reach communication system includes a plurality of communication SERDES that communicate data over a short reach channel medium such as a backplane connection (e.g., PCB trace) between, for example, chips located on a common PCB. A multi-level modulated data signal is generated to transmit/receive data over the short reach channel medium. Multi-level modulated data signals, such as four-level PAM, reduce the data signal rate therefore reducing insertion loss, power, complexity of the circuits and required chip real estate.