Photoemitter Bond Wire Layout for High-Frequency Crosstalk Reduction

Solution Overview

Problem

Bond wires connecting contact pads on integrated circuit (IC) chips to substrates are prone to crosstalk at high signal frequencies due to their unshielded nature, especially when multiple transducers are closely spaced, leading to signal interference.

Innovation Solution

The implementation of an array of photoemitter devices with bond wires routed in opposite directions relative to adjacent devices, either by rotating or mirroring the photoemitter devices, and mounting the IC chip within a recess to minimize bond wire length and increase separation between bond wires, thereby reducing crosstalk.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If bond wires are used to connect contact pads to substrate, then ease of manufacture and reliability are improved, but crosstalk increases at high signal frequencies

Engineering Contradiction:

Improveconnection reliabilityVSAvoidcrosstalk

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by routing bond wires for adjacent photoemitter devices in opposite directions relative to the device array axis. Specifically, bond wires for odd-numbered devices are routed on one side of the array while bond wires for even-numbered devices are routed on the opposite side, creating an asymmetric routing pattern that reduces electromagnetic coupling and crosstalk between adjacent signal paths.

Inventive Principle:

Principle #4Asymmetry

2Productivity

If multiple transducers are closely spaced to increase data rate, then productivity is improved, but crosstalk between bond wires increases

Engineering Contradiction:

Improvedata communication rateVSAvoidcrosstalk

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by routing bond wires for adjacent photoemitter devices in opposite directions relative to the device array axis. Specifically, bond wires for odd-numbered devices are routed on one side of the array while bond wires for even-numbered devices are routed on the opposite side, creating an asymmetric routing pattern that reduces electromagnetic coupling and crosstalk between adjacent signal paths.

Inventive Principle:

Principle #4Asymmetry

3Ease of manufacture

If bond wire length is increased to accommodate routing, then ease of manufacture is improved, but electromagnetic coupling and crosstalk increase

Engineering Contradiction:

Improverouting flexibilityVSAvoidelectromagnetic coupling

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies asymmetry by routing bond wires for adjacent photoemitter devices in opposite directions relative to the device array axis. Specifically, bond wires for odd-numbered devices are routed on one side of the array while bond wires for even-numbered devices are routed on the opposite side, creating an asymmetric routing pattern that reduces electromagnetic coupling and crosstalk between adjacent signal paths.

Inventive Principle:

Principle #4Asymmetry

Data Source

PatentUS11855415B2High frequency signal coupling to surface emitters

Publication Date: 2023.12.26 CREDO TECHNOLOGY GROUP LTD

AI summary

To reduce crosstalk between bond wires, one illustrative integrated circuit includes an array of photoemitters arranged along a centerline, with adjacent photoemitters having contact pads on opposite sides of the centerline. An illustrative assembly includes an integrated circuit chip having an array of photoemitter contact pads; a printed circuit board having a recess in which the integrated circuit chip is mounted; and bond wires connecting the contact pads with respective contact pads on the printed circuit board. An illustrative cable connector includes a module that optically couples optical fibers to an array of photoemitters on an integrated circuit chip mounted to a printed circuit board. Each photoemitter has contact pads connected to the printed circuit board contact pads by bond wires, the bond wires for each photoemitter being routed in an opposite direction relative to the bond wires for any adjacent photoemitters in the array.