Laser Source Driving Circuit Layout Crosstalk Reduction
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Solution Overview
Problem
The existing circuit layout of laser source driving circuits suffers from signal noise due to crosstalk, which affects the accuracy of distance measurement in laser rangefinders.
Innovation Solution
The circuit layout is redesigned to shorten the first and second traces, with specific configurations of conductive lines and via holes connecting electrical elements, reducing the total length of these traces from 25 mm to between 13 mm and 19 mm, thereby minimizing crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the circuit layout uses conventional trace routing with longer paths to connect electrical elements, then the layout is easier to implement with standard design practices, but signal noise due to crosstalk increases and measurement accuracy deteriorates
Solution Approach 1:
The patent applies asymmetry by deliberately designing the first and second traces with different routing paths and lengths. The first trace connecting the capacitor to the laser element is optimized to be shorter than conventional designs, while the second trace is routed to achieve specific length relationships. This asymmetric layout breaks the symmetry that typically causes balanced crosstalk, thereby reducing signal noise and improving measurement accuracy.
Solution Approach 2:
The patent implements parameter changes by specifying precise trace length parameters - the first trace is designed with a length of 13-19mm (significantly shorter than conventional designs), and the second trace is designed to have a specific length relationship with the first. By changing these critical dimensional parameters, the patent reduces the antenna effect and crosstalk, thereby improving signal quality and distance measurement accuracy.
2Measurement precision
If the trace lengths are reduced to minimize crosstalk, then measurement accuracy improves, but the layout complexity and difficulty of precise manufacturing increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-designing the optimal trace lengths (13-19mm for the first trace) before manufacturing. The layout is carefully planned in the design stage to incorporate via holes and conductive lines that achieve the target length specifications, so that during manufacturing, the critical dimension control is already built into the design margins, making it easier to achieve the required precision.
Solution Approach 2:
The patent uses via holes as intermediary elements to connect different layers and to precisely control trace lengths. The via holes serve as fixed reference points that mediate between the design requirements for short trace lengths and the manufacturing capabilities. By routing traces through strategically placed via holes, the patent achieves precise length control (13-19mm) that balances crosstalk reduction with manufacturing feasibility.
Data Source
AI summary
A circuit layout of laser source driving circuit includes a laser element, a first layout layer, a second layout layer, a first trace and a second trace. The first layout layer includes a first transistor. The second layout layer includes a second transistor, a capacitor, a first resistor and a second resistor. The first trace includes a first conductive line connecting the first resistor and the capacitor and a second conductive line connecting the capacitor and the laser element. The second trace includes a third conductive line connecting the second resistor and the second transistor, a fourth conductive line connecting the second transistor and the first transistor and a fifth conductive line connecting the first transistor and the laser element. A total length of the first trace and the second trace ranges from 13 mm to 19 mm.