Serial Data Transmission Circuit Synchronization Recovery
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Solution Overview
Problem
In serial data transmission using a clock data recovery (CDR) scheme, synchronization errors can lead to significant disturbances in image data transmission, especially when the synchronization shift exceeds a certain number of words, causing reception errors and image distortion, particularly in electronic devices like display panels.
Innovation Solution
A transmission technique that includes an encoder generating D symbols with embedded clock signals and K symbols for synchronization, where K symbols are allocated at specific intervals, allowing for rapid reestablishment of synchronization even if a synchronization error exceeds the period of the third code, using a higher synchronization code at a shorter interval than the initialization code to correct the current position of serial data without needing the next initialization code.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single initialization code K0 is used at the beginning of each scrambling period, then the system can establish synchronization, but if a synchronization error exceeds the interval to the next K0, the system cannot recover until the next initialization code
Solution Approach 1:
The single initialization code K0 is segmented into multiple types of synchronization codes: initialization code K0 (reset function), higher synchronization code K2 (coarse correction), and lower synchronization code K1 (fine correction). This segmentation allows different levels of synchronization recovery depending on the error magnitude, enabling faster recovery without losing the reset capability of the original K0.
Solution Approach 2:
Synchronization codes are transmitted periodically at fixed intervals throughout the data stream. The higher synchronization code K2 appears at regular intervals (e.g., every 100 words), providing periodic opportunities for synchronization recovery without requiring the full initialization sequence, thus reducing average recovery time.
2Reliability
If synchronization codes are transmitted frequently at short intervals, then synchronization can be recovered quickly, but the data transmission efficiency decreases due to more overhead codes
Solution Approach 1:
Different regions of the data stream receive different levels of synchronization protection. Critical regions (where K2 codes are placed at shorter intervals) receive stronger synchronization support, while other regions use standard spacing. This local differentiation maintains synchronization reliability where needed without uniformly reducing data transmission efficiency across the entire stream.
Solution Approach 2:
Instead of providing full initialization codes (K0) at every possible interval, the system applies partial synchronization action using lighter-weight K2 and K1 codes at intermediate intervals. These codes provide sufficient synchronization for typical error conditions without the full overhead of repeated K0 initialization sequences, achieving adequate protection with reduced overhead.
3Device complexity
If the system uses conventional scrambling with limited synchronization codes, then the implementation is simple, but image disturbance occurs when synchronization errors exceed the code interval
Solution Approach 1:
The higher synchronization code K2 acts as an intermediary between the initialization code K0 and the lower synchronization code K1. It provides a middle-level synchronization reference that can recover from moderate errors without requiring full initialization, thereby preventing image disturbance in cases where K0 intervals are too long, while maintaining a simpler structure than full K0 sequencing.
4Reliability
If the system waits for the next initialization code to recover synchronization, then the synchronization recovery is reliable, but the recovery time becomes unacceptably long
Solution Approach 1:
The higher synchronization code K2 is placed in advance at predictable intervals throughout the data stream, creating preliminary synchronization reference points before errors can accumulate to critical levels. When synchronization errors occur, these pre-positioned K2 codes provide immediate recovery opportunities, eliminating the need to wait for distant K0 initialization codes and significantly reducing recovery time while maintaining reliability.
Data Source
AI summary
Transmission circuit for transmitting serial data with superposed clock signal includes encoder to scramble parallel data of information and apply predetermined coding scheme to generate D symbols having clock signal embedded therein, and to output alternately continuous predetermined number of the D symbols and one of K symbols as synchronization control codes for the scrambling; and parallel-to-serial converter configured to convert the D symbols and the K symbols output from the encoder into serial data, wherein, for each period of the scrambling, the encoder outputs K symbols, each of which is allocated to one of the first code indicating beginning of the period of the scrambling, the second code allocated at equal interval among remaining ones of the K symbols other than that for the first code, and a third code allocated among remaining ones of the K symbols other than those for the first code and the second code.