Laser Driver Edge Control for Signal Distortion
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Solution Overview
Problem
Direct modulated laser drivers face non-linear behavior issues, leading to degraded eye quality and increased bit error rates due to non-linear rising and falling edges, which classic de-emphasis techniques exacerbate by introducing ringing behavior and jitter.
Innovation Solution
A driver system that selectively applies delays to rising and falling edges of input signals, using multiplexers and amplifiers to create a driver output signal with emphasis or de-emphasis, allowing for independent control of high-frequency energy addition to compensate for signal distortion during optical transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If classic de-emphasis is applied to compensate for channel loss, then high frequency power is added to the transmitted signal, but ringing behavior and jitter are exacerbated
Solution Approach 1:
The patent segments the de-emphasis function into separate rising edge de-emphasis and falling edge de-emphasis paths. Each path independently controls the de-emphasis amount for its respective edge type, allowing selective application of de-emphasis to compensate for channel loss while avoiding excessive de-emphasis on edges that would generate ringing behavior.
Solution Approach 2:
The patent applies different de-emphasis characteristics to different parts of the signal - specifically, different de-emphasis amounts are applied to rising edges versus falling edges. This local differentiation allows the system to add high frequency power where needed while avoiding ringing in sensitive regions.
2Reliability
If de-emphasis is applied to improve signal quality, then eye margin degradation is reduced, but jitter increases
Solution Approach 1:
By separating de-emphasis control into independent rising edge and falling edge paths, the system can optimize eye margin for each edge type without uniformly increasing jitter across all signal transitions.
Solution Approach 2:
The patent dynamically adjusts the de-emphasis amount parameter based on the signal edge type and transmission conditions. By changing the de-emphasis parameter selectively for rising versus falling edges, the system improves eye margin while controlling jitter through optimized parameter selection.
3Reliability
If separate control of rising and falling edge delays is implemented, then signal quality is improved, but device complexity increases
Solution Approach 1:
The patent divides the delay control function into separate rising edge delay and falling edge delay circuits, each with independent control. This segmentation enables precise signal quality optimization for each edge type while using modular circuit design to manage complexity.
Solution Approach 2:
The patent employs a universal delay control architecture that can be configured for different delay amounts and characteristics through programmable control. This multi-functional approach allows separate rising and falling edge delay control while reusing common circuit blocks, thereby managing device complexity.
Data Source
AI summary
A driver system with emphasis or de-emphasis control of optic signal generator comprising an input configured to receive an input signal that is to be transmitted as an optic signal. Also part of this system is a rising edge delay creating a first delay signal relative to the input signal and a falling edge delay creating a second delay signal relative to the input signal. A multiplexer receives the first delay signal and the second delay signal and selectively outputs either the first delay signal and the second delay signal to an amplifier. A first amplifier amplifies the input signal to create an amplified input and a second amplifier amplifies the multiplexer output signal to create a de-emphasis signal. A summing junction subtracts the de-emphasis signal from the amplified input to create a driver output signal. The rising and falling edge delays may each comprise two more delays.