EMI Filter in Optical Transceivers for Signal Integrity
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Solution Overview
Problem
Optical transceivers generate unwanted electromagnetic interference (EMI) that degrades nearby circuit performance and increases data signal error rates, necessitating a reduction in EMI levels while adhering to regulatory limits.
Innovation Solution
Incorporating a filter that capacitively and inductively couples the electrical signal path to ground potential, specifically designed to reduce EMI amplitude at predetermined frequencies, within the optical transmitter and receiver components, including a housing that may also provide EMI shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a filter is added to reduce EMI amplitude at predetermined frequencies, then EMI levels are reduced below regulatory limits, but device complexity increases
Solution Approach 1:
The patent introduces an EMI filter as an intermediary component between the electrical signal generator and the interface. This filter specifically targets and attenuates EMI at predetermined frequencies (such as clock frequencies and their harmonics) while allowing the desired electrical signals to pass through. The filter acts as a mediator that selectively removes harmful frequency components without affecting the overall signal integrity, thereby reducing EMI levels below regulatory limits while maintaining device functionality.
2Object-affected harmful factors
If shielding is applied to reduce EMI radiation, then harmful EMI effects on external circuitry are reduced, but device complexity and cost increase
Solution Approach 1:
The patent extracts and addresses the EMI problem at its source by using filtering to remove harmful frequency components from the electrical signals before they can radiate through the interface. Instead of applying broad-spectrum shielding to the entire device, the solution selectively targets and removes only the problematic EMI frequencies (such as clock frequencies and harmonics) using filters placed at strategic locations in the electrical signal path. This approach reduces EMI radiation effects on external circuitry while avoiding the complexity and cost of comprehensive shielding.
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
The filter significantly reduces EMI to acceptable levels without affecting signal quality, ensuring compliance with regulatory limits and minimizing interference with external circuitry.
Implementation Method 1
a filter downstream from the electrical signal generator configured to reduce an amplitude of electromagnetic interference (EMI) at the predetermined frequency below a predetermined maximum value
Implementation Method 2
a filter downstream from the electrical signal generator configured to reduce an amplitude of electromagnetic interference (EMI) at the predetermined frequency below a predetermined maximum value
Data Source
AI summary
Embodiments of the disclosure pertain to an optical transmitter and/or receiver comprising an electrical signal generator configured to generate an electrical signal that is unshielded or unshieldable at a predetermined frequency, a filter downstream from the electrical signal generator configured to reduce an amplitude of electromagnetic interference (EMI) at the predetermined frequency below a predetermined maximum value, an interface through which the EMI can pass in the absence of the filter, and an optical component configured to receive the electrical signal or provide an input signal to the electrical signal generator. A method of reducing EMI in an optical transmitter and/or receiver using the electrical signal generator, the filter and the optical component is also disclosed.