Parallel Laser Driver EMI Reduction via Phase Delay
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Solution Overview
Problem
Parallel laser drivers in transceivers generate higher electromagnetic interference (EMI) due to asymmetric electrical waveforms, leading to performance degradation and cross-talk issues, especially when multiple drivers are used in parallel.
Innovation Solution
Implementing a method where delays of signals are adjusted to create phase differences between adjacent signals, satisfying a phase delay requirement, which reduces EMI emissions by configuring the phase differences to cancel out radiated fields and minimize cross-talk between laser drivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple parallel laser drivers are implemented in the transceiver, then the transmission capacity and data rate are improved, but the electromagnetic interference emission increases
Solution Approach 1:
The patent divides the signal transmission into multiple parallel channels (e.g., 4 channels) to increase transmission capacity. Each channel is independently managed with specific phase relationships, allowing the system to achieve higher productivity while controlling EMI through structured segmentation of the electromagnetic fields.
Solution Approach 2:
The patent introduces asymmetric phase delays to adjacent laser drivers where the phase difference does not equal 180 degrees. This asymmetric configuration prevents complete constructive interference that would occur with symmetric arrangements, thereby reducing peak EMI emissions while maintaining high transmission capacity through multiple parallel channels.
2Speed
If multiple parallel laser drivers are implemented, then the data transmission rate is improved, but the cross-talk between drivers increases
Solution Approach 1:
The patent addresses cross-talk by introducing a temporal dimension through phase delays. Instead of only spatial separation, the invention uses time-domain phase relationships (phase differences between 0 and 180 degrees) to create constructive and destructive interference patterns that reduce cross-talk between parallel channels while maintaining high data transmission rates.
3Reliability
If asymmetric electrical waveforms are used to meet transceiver requirements, then the signal integrity is improved, but the EMI emission at bit rate frequency increases
Solution Approach 1:
The patent converts the harmful EMI effect into a beneficial one by deliberately introducing phase delays that create destructive interference at the bit rate frequency. The asymmetric waveforms that originally caused strong EMI emissions are now configured with specific phase relationships (differences between 0 and 180 degrees) that cause the electromagnetic fields to cancel each other out at problematic frequencies, while maintaining signal integrity through the controlled asymmetric structure.
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
Significantly reduces EMI emissions and cross-talk between parallel laser drivers, as demonstrated by simulation results showing a 10 dB reduction in EMI levels across all bit rates, enhancing the performance of multi-channel transmitters.
Implementation Method 1
Electromagnetic interference (EMI) may include disturbance that affects an electrical circuit due to either electromagnetic induction or electromagnetic radiation emitted from an external source
Implementation Method 2
configuring the phase differences to cancel out radiated fields
Data Source
AI summary
A method of reducing electromagnetic interference in a multi-channel transmitter is described. The method may include receiving multiple signals configured to be transmitted through multiple channels. The method may additionally include adjusting delays of the multiple signals to generate multiple delayed signals. Each two adjacent delayed signals may be configured to have a corresponding phase difference that satisfies a phase delay requirement. The method may additionally include generating multiple load signals from the multiple delayed signals.