COIC Amplifier Integration for Optical Signal Integrity
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Solution Overview
Problem
Conventional high-speed optical transceivers face performance issues due to impedance disruptions caused by large bias tees and hot bar soldered flex circuits, which disrupt signal integrity and increase costs, leading to closed PAM4 eye diagrams despite high-quality EML and amplifiers.
Innovation Solution
The design incorporates a COIC with integrated amplifier and bias plane operating at nominal voltage, minimizing electrical connections between components and using thin epoxy joints and a lead frame with a bridge to address thermal expansion mismatches, while the COIC supports the EML at a positive voltage, allowing for efficient modulation and reduced channel losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bias tees are used to connect amplifiers to modulators, then amplifiers can operate at positive voltages while modulators are biased at negative voltages, but the bias tees physically disrupt impedance and move amplifiers farther away, closing the PAM4 eye diagram
Solution Approach 1:
The patent removes the bias tee component entirely from the signal path. Instead of using a bias tee to accommodate voltage differences, the design directly connects the amplifier substrate to the modulator substrate, eliminating the impedance-disrupting component while maintaining voltage compatibility through direct substrate coupling
Solution Approach 2:
The patent merges the amplifier and modulator into a single integrated package where both components share a common substrate. This integration eliminates the need for external bias tees and reduces the physical distance between components, thereby maintaining signal integrity while supporting different voltage requirements
2Ease of operation
If hot bar soldered flex circuits are used to connect TOSA to PCB, then mechanical constraints are avoided, but the large PCB pad size and excess solder create impedance disruptions
Solution Approach 1:
The patent removes the hot bar soldered flex circuit from the connection path. Instead, it uses direct substrate-to-substrate bonding between the TOSA package and the PCB, eliminating the large pad sizes and excess solder that cause impedance disruptions while maintaining mechanical flexibility through the package design
Solution Approach 2:
The patent replaces the mechanical hot bar soldering process with direct substrate bonding technology. This substitution eliminates the need for large solder pads and excess solder material, thereby maintaining impedance continuity while achieving the necessary mechanical connection
3Adaptability or versatility
If amplifiers are placed farther from EML due to bias tee requirements, then voltage compatibility is achieved, but channel losses increase and PAM4 eye diagram closes
Solution Approach 1:
The patent merges the amplifier and EML into a single integrated package where both components are located in close proximity on the same substrate. This integration maintains voltage compatibility through direct substrate coupling while minimizing the distance between components, thereby reducing channel losses and maintaining signal quality
Data Source
AI summary
An optical communication system, device, and method are disclosed. An illustrative optical communication system is disclosed to include a carrier Integrated Circuit (IC) chip having an amplifier circuit, a bias plane, and a ground plane. The amplifier circuit, bias plane, and the ground plane may each operate at or above a nominal voltage of zero volts. A laser diode may be integrated with an electro-absorption modulator into a single IC chip, where the laser diode is mounted on the carrier IC chip and is electrically connected with the amplifier circuit of the carrier IC chip through a bond wire.