Optical Receiver Slice-Level Adjustment for Jitter Reduction
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Solution Overview
Problem
High-speed optical receivers face challenges in reliable data detection due to non-idealities and noise in the transimpedance amplifier, leading to signal corruption and increased jitter, which degrades the performance of clock-and-data recovery circuits.
Innovation Solution
Implementing offset compensation and slice-level adjustment mechanisms in the optical receiver, where offset compensation is applied through a feedback loop and slice-level adjustment is applied at specific sampling instants to minimize jitter and maintain signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If offset compensation is applied continuously through feedback loop, then offset correction is improved, but jitter increases and signal integrity deteriorates
Solution Approach 1:
The patent segments the offset compensation function into two distinct operational modes: continuous feedback loop operation for initial offset correction, and discrete slice-level adjustment at specific sampling instants for fine-tuning. This segmentation allows the system to benefit from both continuous correction and periodic stabilization, resolving the contradiction between correction accuracy and signal integrity.
Solution Approach 2:
The patent implements periodic slice-level adjustment at specific sampling instants (e.g., halfway between zero-crossings) rather than continuous adjustment. This periodic action allows the system to maintain offset correction while periodically stabilizing the signal, reducing jitter and preventing the degradation of signal integrity that occurs with continuous adjustment.
2Measurement precision
If slice-level adjustment is applied continuously, then data detection accuracy is improved, but jitter increases and clock positioning deteriorates
Solution Approach 1:
The patent applies slice-level adjustment periodically at specific sampling instants rather than continuously. This periodic application maintains data detection accuracy by adjusting the decision threshold when needed, while minimizing jitter by avoiding continuous interference with the signal timing and clock recovery processes.
Solution Approach 2:
The patent performs slice-level adjustment at predetermined sampling instants (e.g., halfway between zero-crossings) before actual data sampling occurs. This preliminary adjustment ensures the decision threshold is optimized in advance, improving data detection accuracy without introducing jitter during the critical sampling and clock recovery phases.
3Adaptability or versatility
If slice-level adjustment is applied at arbitrary instants, then adaptability is improved, but clock-and-data recovery performance deteriorates
Solution Approach 1:
The patent applies slice-level adjustment at specific local sampling instants (e.g., halfway between zero-crossings) rather than arbitrarily throughout the signal. This localized application maintains adaptability to handle asymmetric noise distributions at critical decision points, while preserving clock-and-data recovery performance by avoiding interference with zero-crossing detection and timing recovery processes.
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 proposed solution effectively reduces jitter and improves the reliability of data detection by decoupling offset compensation and slice-level adjustment, ensuring accurate clock positioning and reduced bit errors, thereby enhancing the overall performance of the optical receiver.
Implementation Method 1
The light produced by the VCSEL is coupled to an optical medium (e.g., fiber or waveguide) and sensed at the receiver by, for example, a photodiode (PD)
Data Source
AI summary
In one embodiment, a receiver may receive a signal from a transmitter. The receiver may include a first sampler that may sample the signal when the value of the signal is zero. The receiver may further include a second sampler that may sample the signal halfway between a time when the first sampler samples the signal and the next time when the first sampler samples the signal to produce a set of sampled values. The receiver may be further operable to determine that a sampled value in the set of sampled values is a logic 1 if the sampled value is greater than the value of a reference voltage and that the sampled value is a logic 0 if the sampled value is less than the value of the reference voltage.