Optical Burst Receiver AC DC Coupling Interface
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Solution Overview
Problem
In high-speed optical networks, the medium access control (MAC) module and optical transceiver often operate at different DC levels, leading to improper reception of burst data signals due to biased DC levels, which can result in data loss, especially in communication standards like Gigabit PON and XGPON.
Innovation Solution
An alternating current (AC) coupling method is introduced, utilizing a hold-over pattern generated by the MAC module to interface with the optical transceiver, ensuring proper reception of burst data signals by unbiasing DC levels through an AC coupling circuit, and switching between AC and DC coupling modes based on signal detection and reset signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DC coupling is used to interface between optical transceiver and MAC module, then data transmission continuity is maintained, but signal integrity deteriorates due to DC level mismatch
Solution Approach 1:
An AC coupling circuit is introduced as an intermediary component between the optical transceiver and MAC module. This circuit includes a coupling capacitor that blocks DC components while allowing AC signal components to pass, thereby eliminating the DC level mismatch issue without requiring complex level-shifting circuitry or signal processing.
2Reliability
If AC coupling is used to unbias DC levels, then signal integrity is improved, but data loss occurs during long sequences of identical bits or between bursts
Solution Approach 1:
A hold-over pattern generator is introduced that produces a predetermined AC-balanced signal pattern in advance. This pattern is stored in a buffer and automatically activated when burst data reception ends or during long sequences of identical bits, ensuring continuous AC-balanced signal delivery to the MAC module without requiring complex real-time adjustment or risking data loss.
3Reliability
If hold-over pattern is continuously input to AC coupling circuit, then AC balance is maintained, but signal accuracy deteriorates during burst data reception
Solution Approach 1:
The system dynamically switches between two operational modes based on real-time signal detection: during burst data reception, the actual received signal is fed to the AC coupling circuit for accurate data processing; during idle periods or long sequences of identical bits, the hold-over pattern is activated to maintain AC balance. This dynamic adaptation ensures both signal accuracy during transmission and AC balance during idle periods.
Data Source
AI summary
A method for enabling AC coupling or DC coupling when receiving burst data signals comprises generating a hold-over pattern, wherein the hold-over pattern is a AC balanced pattern when an AC coupling is required and a low-logic value signal when a DC coupling is required; inputting the generated hold-over pattern to an AC coupling circuit, when no burst data signal is received; inputting only a received burst data signal to the AC coupling circuit, during the reception of such signal; and upon receiving of the entire burst data signal, generating a reset signal causing to input the generated holdover pattern to an AC coupling circuit.