Transceiver PCB IC Layout for Signal Integrity and Footprint Reduction

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing transceiver printed circuit boards face challenges in reducing the size of ICs while maintaining signal integrity and adhering to multi-source agreements, as integrating all functionalities into a single IC requires balancing size reduction with optical and IC placement constraints, leading to high costs due to large silicon content.

Innovation Solution

A transceiver printed circuit board design integrates the functionality of a transimpedance amplifier, laser driver, and clock and data recovery into a single IC, optimizing IC placement to reduce footprint and cost, with the photodiode and laser positioned to maintain the required optical pitch, allowing for a significant reduction in overall IC size and surface area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple separate ICs (LD IC, TIA IC, CDR IC) are used, then each IC can be optimized for its specific function, but the total IC footprint increases and cost increases due to larger silicon content

Engineering Contradiction:

Improvesignal integrityVSAvoidIC footprint

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent combines the functionality of three separate ICs (LD IC, TIA IC, and CDR IC) into a single integrated IC. This merging approach reduces the total silicon content and footprint while maintaining the necessary functional separation through internal architecture design, directly addressing the contradiction between signal integrity and IC footprint.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The integrated IC performs multiple functions (laser driving, transimpedance amplification, and clock data recovery) simultaneously within a single chip. This multi-functionality allows the system to achieve the performance of multiple separate ICs with reduced overall footprint and lower cost, resolving the contradiction between functional optimization and area efficiency.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Area of stationary object

If the IC size is reduced to lower cost, then silicon content and manufacturing cost decrease, but maintaining proper optical pitch and signal integrity becomes more difficult

Engineering Contradiction:

ImproveIC footprintVSAvoidsignal integrity

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The patent repositions the integrated IC relative to the optical components (PIN photodiode and VCSEL laser) by utilizing the fourth dimension (vertical stacking or repositioning on the PCB). This allows the IC to be placed closer to the optical components, reducing wire-bond length and maintaining signal integrity while keeping the IC footprint small and cost-effective.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent introduces the PCB as an intermediary platform that enables optimized placement of the integrated IC relative to the optical components. Through careful PCB layout and routing, the system maintains proper optical pitch requirements while allowing the IC to be positioned for optimal electrical connection, thus preserving signal integrity with reduced IC size.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the IC is positioned closer to optical components to reduce wire-bond length, then signal integrity improves, but the layout flexibility and available PCB surface area are reduced

Engineering Contradiction:

Improvesignal integrityVSAvoidPCB surface area

Core Design Contradiction:

ReliabilityVSArea of stationary object

Solution Approach 1:

The patent employs asymmetric layout design where the integrated IC is positioned asymmetrically relative to the optical components on the PCB. This asymmetric arrangement optimizes the wire-bond paths for signal integrity while preserving adequate PCB surface area for other components and routing, resolving the contradiction between proximity for signal quality and overall layout flexibility.

Inventive Principle:

Principle #4Asymmetry

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This design achieves an 11% to 35% reduction in IC footprint and corresponding cost savings, reduces wire-bonding complexity, and simplifies component placement, enhancing signal integrity and layout efficiency.

Implementation Method 1

a PIN photodiode 40

Methodology Applied

Scientific EffectPhotoelectric Effect: Photoelectric Effect

Implementation Method 2

a VCSEL laser 50

Methodology Applied

Scientific EffectLaser: Laser

Data Source

PatentUS10551582B2Layout of optical engine components and integrated circuits on a transceiver printed circuit board

Publication Date: 2020.02.04 FOXCONN INTERCONNECT TECHNOLOGY LTD

AI summary

A transceiver printed circuit board (PCB) includes an integrated circuit (IC) with at least two different functionality, a photodiode and a laser. The IC has a first side, a second side opposite to the first side, a third side connecting the first side and the second side, and a fourth side opposite to the third side. The photodiode and the laser are both located in a first space beside the first side. The functionality of a transimpedance amplifier, a laser driver, and a clock and data recovery is integrated into the IC.