DC-Balanced Encoding Circuit With Fewer Signal Transitions
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Solution Overview
Problem
Manchester encoding, while effective for DC-balancing and synchronization, suffers from significant bandwidth and power consumption penalties due to its 100% bandwidth overhead and excessive signal transitions, which are prohibitive in many applications.
Innovation Solution
An encoding circuit and method that generates a DC-balanced sequence of words with reduced signal transitions, consuming less energy by alternating and replicating bits to achieve DC-balance, potentially using look-up tables, state machines, and shift-register sequences, resulting in a sequence with substantially twice as many words as the original, thereby minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Manchester encoding is used to ensure DC-balancing and synchronization, then DC-balance and synchronization are achieved, but bandwidth overhead increases to 100% and power consumption increases due to excessive signal transitions
Solution Approach 1:
The patent applies partial action by ensuring DC-balance only when necessary (when the number of 1s and 0s would be unequal) rather than forcing transitions on every bit. The encoder selectively adds balancing bits only when the running digital sum indicates an imbalance, rather than applying uniform transitions to all data bits as in Manchester encoding.
Solution Approach 2:
The patent changes the encoding parameter from fixed transitions per bit (Manchester) to variable transitions based on data content. The encoding scheme adapts the number of transitions based on the actual bit pattern, using 0, 1, or 2 transitions per data bit depending on whether DC-balance is needed, thereby reducing overall power consumption while maintaining reliability.
2Reliability
If Manchester encoding is used to ensure DC-balancing, then any given data packet is DC-balanced, but bandwidth overhead increases to 100%
Solution Approach 1:
The patent uses partial action by applying DC-balance corrections only when necessary rather than to every bit. The encoder monitors the running digital sum and selectively adds balancing sequences only when the imbalance threshold is exceeded, thereby reducing the average number of transmitted bits while ensuring DC-balance is achieved when needed.
Solution Approach 2:
The patent segments the data stream into units where DC-balance is evaluated and corrected independently. By processing data in selectable units (bits, pairs of bits, or larger groups) and applying balancing corrections at appropriate boundaries, the encoder achieves DC-balance without requiring every single bit to be encoded with transitions, improving bandwidth efficiency.
3Reliability
If signal transitions are guaranteed in every encoded bit for synchronization, then synchronization is achieved, but energy consumption increases due to transitions driving capacitors
Solution Approach 1:
The patent applies partial action by providing synchronization transitions only when necessary for maintaining sync rather than on every bit. The encoder ensures at least one transition occurs within each selectable unit when needed for synchronization, but allows zero transitions in units where the data pattern naturally provides sufficient timing information, reducing overall energy dissipation.
Solution Approach 2:
The patent maintains continuous synchronization capability by ensuring that within each selectable unit (bit, pair, or group), at least one transition occurs when synchronization is required. This continuous provision of transition opportunities keeps the receiver synchronized without requiring transitions on every single bit, reducing energy loss while maintaining reliable synchronization.
Data Source
AI summary
Embodiments of an encoding circuit to communicate a sequence of words are described. This encoding circuit includes an encoding module that is configured to receive a first sequence of words and to generate a DC-balanced second sequence of words based on the first sequence of words, where communicating the second sequence of words consumes less energy than communicating a third sequence of words that includes words in the first sequence of words alternating with words in the inverse of the first sequence of words. In addition, the second sequence of words includes substantially twice as many words as the first sequence of words.