Signal Conditioning Negotiation for AC-Coupled DC Offset Removal
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Solution Overview
Problem
In passive optical networks, AC coupling capacitors between transmitters and receivers often face issues due to input-level dependent DC offsets, leading to inadequate discharge during signal transmission, resulting in failed signal recovery and timing budget violations, especially in scenarios without host reset signals.
Innovation Solution
The use of both off-chip and on-chip signaling allows for optimized electrical signal negotiation, enabling the transmitter and receiver to settle independently before data transmission, ensuring effective DC offset removal and improved signal recovery through staggered instruction timing and pulse management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a host reset signal is used to discharge AC coupling capacitors, then DC offset removal is achieved, but adequate discharge time is not provided and timing budget is violated
Solution Approach 1:
The patent segments the reset function into two independent parts: a first reset signal for the transmitter and a second reset signal for the receiver. This allows each device to receive reset instructions at different times, enabling the AC coupling capacitors to discharge adequately before data transmission begins, thus resolving the timing budget violation while ensuring reliable signal recovery.
Solution Approach 2:
The patent applies preliminary action by issuing the first reset signal to the transmitter before the second reset signal to the receiver. This staggered timing ensures that the transmitter has sufficient time to discharge its AC coupling capacitors before the receiver begins processing signals, preventing timing budget violations while maintaining signal recovery reliability.
2Loss of time
If no host reset signal is provided during registration period, then timing budget is maintained, but DC offset discharge is insufficient and signal transmission fails
Solution Approach 1:
The patent implements self-service by enabling the transmitter and receiver to autonomously manage their own reset signaling during the registration period. The transmitter generates and transmits a reset signal to itself, and the receiver responds with its own reset signal, eliminating the need for external host intervention while ensuring adequate DC offset discharge and maintaining timing budget compliance.
Solution Approach 2:
During the registration period, the patent applies preliminary action by having the transmitter initiate a reset signal before data transmission begins. This allows the AC coupling capacitors to discharge in advance, ensuring that when actual data transmission starts, the timing budget is maintained and signal transmission reliability is ensured without requiring a host reset signal.
3Device complexity
If simultaneous reset signaling is used for transmitter and receiver, then device complexity is reduced, but AC coupling capacitor discharge is insufficient
Solution Approach 1:
The patent segments the simultaneous reset signaling into sequential reset signals - a first reset signal for the transmitter and a second reset signal for the receiver transmitted at different times. This segmentation allows each device adequate time to discharge its AC coupling capacitors while maintaining relatively simple device architecture, thus resolving the contradiction between device complexity and discharge reliability.
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
After transmitting first electrical signals to a receiver, a transmitter receives a burst absent mode signal from the receiver. While in a ready state, the transmitter receives a signal including a data burst, converts the signal to second electrical signals, including a settled DC offset, and transmits the second electrical signals to the receiver. The receiver transmits the burst absent mode signal to the transmitter after receiving the first electrical signals, detects a presence of the second electrical signals. In response to detecting the presence of the second electrical signals, the receiver removes the DC offset from the second electrical signals to generate output signals, and causes transmitting the output signals to a subsequent device. The receiver removes the DC offset by causing an instruction to discharge AC coupling capacitors. The burst absent mode signal is generated using a host reset instruction or an internally generated instruction.