Optical Module Differential Pair Layout for Phase Shift Cancellation
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Solution Overview
Problem
Differential transmission line pairs in optical modules experience phase shift due to length differences, leading to instability in high-frequency signals.
Innovation Solution
The optical module design includes a pair of first and second differential transmission line pairs with different lengths, where the longer first line is connected to the shorter second line and vice versa through lead pins, canceling phase shift and stabilizing high-frequency signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a differential transmission line pair is used to stabilize high-frequency signals, then signal stability is improved, but length difference between the pair of lines causes phase shift and destabilizes the signal
Solution Approach 1:
The patent applies asymmetry by intentionally creating unequal lengths in the differential transmission line pairs. The first substrate has first lines with different lengths, and the second substrate has second lines with different lengths. This asymmetric design allows the phase shifts in the two lines to cancel each other out, resolving the contradiction between using differential pairs for stability and the phase shift caused by length differences.
Solution Approach 2:
The patent inverts the conventional approach by connecting longer first lines to shorter second lines and shorter first lines to longer second lines through lead pins. This cross-connection strategy reverses the typical length-matching approach and enables phase shift cancellation, thereby stabilizing high-frequency signals despite the asymmetric line lengths.
2Reliability
If lines of different lengths are used to cancel phase shift, then high-frequency signal stability is improved, but the structure becomes more complex
Solution Approach 1:
The patent segments the transmission line structure into two separate substrates, each handling one pair of differential lines with different lengths. This segmentation allows independent optimization of each line pair's length to achieve phase shift cancellation while maintaining manageable structural complexity through modular design.
Solution Approach 2:
The patent distributes the differential transmission line pairs across two different substrates (first substrate and second substrate), adding a dimensional aspect to the design. This spatial distribution allows the implementation of asymmetric line lengths for phase cancellation while organizing the complex structure into manageable layers, reducing overall structural complexity.
Data Source
AI summary
Each of the pair of lead pins has a first portion protruding from the first surface and a second portion protruding from the second surface. Each of the pair of first lines is connected to the first portion. Each of the pair of second lines is connected to the second portion. A photoelectric device is electrically connected to the pair of first lines. A longer one of the pair of first lines is electrically connected to a shorter one of the pair of second lines, through a corresponding one of the pair of lead pins. A shorter one of the pair of first lines is electrically connected to a longer one of the pair of second lines, through another corresponding one of the pair of lead pins.