Dual-Rate DML Signal Calibration Circuit
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Solution Overview
Problem
In high-speed optical communication systems, direct modulation laser (DML) devices experience signal deterioration due to varying input currents, especially at frequencies above 40 Gbps, affecting signal transmission and extraction.
Innovation Solution
A dual-rate DML device with a built-in signal calibration circuit, featuring a light splitting structure, a PD array, and a serial port control structure, which reduces crosstalk and adjusts bonding length and angle to improve signal quality through multistage amplification and equalization, enabling high-quality signal output at 25 Gbps and 28 Gbps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If direct modulation laser mode is used for high-speed transmission, then device complexity and cost are reduced, but signal quality deteriorates at frequencies above 40 Gbps
Solution Approach 1:
The patent segments the laser driver functionality into multiple independent modules: a basic driver circuit for signal generation and a separate calibration circuit for signal quality optimization. This segmentation allows the basic driver to remain simple while the calibration circuit compensates for signal deterioration, resolving the contradiction between device complexity and signal quality at high frequencies.
Solution Approach 2:
The patent implements dynamic parameter adjustment through the calibration circuit, which modifies driver circuit parameters (such as current amplitude and timing) based on detected signal quality metrics. This enables the system to adapt to frequency-dependent signal deterioration, maintaining reliable signal transmission at frequencies above 40 Gbps without requiring a complete redesign of the basic driver architecture.
2Reliability
If signal calibration circuit is added to improve signal quality, then signal transmission reliability improves, but device complexity increases
Solution Approach 1:
The patent merges the calibration circuit with the existing laser driver structure, integrating calibration functions into the same physical package and using shared components where possible. The calibration circuit is designed to work in conjunction with the basic driver rather than as a completely separate system, reducing overall device complexity while maintaining signal transmission reliability.
Solution Approach 2:
The calibration circuit implements self-service functionality by automatically detecting signal quality issues and adjusting driver parameters without external intervention. The system monitors its own output and performs real-time calibration, eliminating the need for complex external calibration equipment and reducing overall system complexity while ensuring reliable signal transmission.
3Reliability
If gold wire bonding length is increased to reduce parasitic inductance, then impedance compatibility improves, but device area increases
Solution Approach 1:
The patent applies local quality optimization by carefully controlling the gold wire bonding characteristics in critical areas. Instead of uniformly increasing bonding length throughout the device, the calibration circuit and driver are positioned to utilize optimized bonding paths only where parasitic inductance critically affects impedance compatibility. This localized approach improves impedance matching without proportionally increasing overall device area.
Solution Approach 2:
The patent addresses the bonding length vs. area contradiction by transitioning to three-dimensional packaging approaches. The gold wire bonds are routed in three-dimensional space around and between components rather than being constrained to a single planar layer, allowing longer effective bonding paths for reduced parasitic inductance without proportionally increasing the two-dimensional device footprint.
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 solution effectively calibrates and improves signal quality by reducing parasitic capacitance and inductance, enhancing impedance compatibility, and reducing power consumption and heat dissipation issues, achieving high-quality signal output at dual modulation frequencies.
Implementation Method 1
a light splitting structure for reflecting and converging a portion of the parallel light onto a PD photosensitive surface
Implementation Method 2
a PD array comprising a plurality of said PD photosensitive surfaces
Data Source
AI summary
The present invention relates to a technical field of optical communications. It relates to a dual-rate DML device and module, and a calibration method, and in particular, to a dual-rate DML device and module having a built-in signal calibration circuit, and a calibration method. According to the present invention, the signal calibration circuit is added into the device; a PD is prepositioned by means of a novel light splitting structure; a control structure for a sequence-divided multi-channel serial signal is utilized to feed back a monitoring signal to an electric driver to adjust drive current; crosstalk between backlight monitoring is reduced; and high-quality signal output under dual modulation frequencies of 25 Gbps and 28 Gbps is realized.