Comma-Synchronized Bit-Stream Decoding for Bit-Skip Recovery
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Solution Overview
Problem
Existing decoding methods for m-bit pattern words from n-bit pattern symbols with m<n require significant logic and space, especially in multi-beam lithography systems, where resources are scarce, and synchronization is challenging due to bit-skip errors during transmission.
Innovation Solution
A method and device that detect an n-bit comma symbol in the input bit-stream to synchronize and decode m-bit pattern words, using a comma position indicator and symbol counter to minimize resource usage and prevent decoding errors, allowing for instantaneous synchronization and reduced propagation of bit-skip errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If complex hardwired lookup-tables and decode functions are used for decoding, then decoding accuracy is improved, but device space and logic resources are consumed
Solution Approach 1:
The patent extracts the synchronization function from the decoding process by using a separate comma detection mechanism. This allows the main decoder to use simpler logic while a dedicated synchronization unit handles bit-skip error recovery, resolving the contradiction between decoding accuracy and device complexity
Solution Approach 2:
The decoding system is segmented into separate functional units: a comma detection unit that identifies synchronization points, and a main decoding unit that processes pattern symbols. This segmentation allows each unit to be optimized independently, improving overall accuracy without proportionally increasing total complexity
2Measurement precision
If additional synchronization resources are added to the decoder, then synchronization accuracy is improved, but available space for modulators and apertures is reduced
Solution Approach 1:
The patent introduces a comma symbol as an intermediary synchronization marker in the bit-stream. This mediator enables the receiver to detect and correct bit-skip errors without requiring complex synchronization circuitry, achieving accurate synchronization with minimal space overhead
Solution Approach 2:
The synchronization mechanism uses simple, lightweight logic circuits that consume minimal space compared to traditional hardwired lookup-tables. These simplified circuits are sufficient for the specific task of comma detection and synchronization state management
3Reliability
If comprehensive decoding logic is implemented, then decoding reliability is improved, but resource consumption increases
Solution Approach 1:
The system performs preliminary synchronization by detecting comma symbols before attempting to decode pattern symbols. This preliminary action ensures that subsequent decoding operations start from known good synchronization points, improving reliability without requiring redundant decoding logic
Solution Approach 2:
The synchronization mechanism uses feedback from comma detection to adjust the decoding state. When a comma symbol is detected, the system resets its synchronization state, preventing error propagation and maintaining high reliability with minimal additional resources
Data Source
AI summary
The invention relates to a invention relates to a method and decoding device for receiving an input bit-stream comprising a sequence of n-bit pattern symbols as well as a unique n-bit comma symbol for synchronization, and for generating therefrom a synchronized output comprising a sequence of m-bit pattern words, with m<n. The comma symbol allows detection of bit-skip in the input bit-stream, so that the output to be synchronized to compensate for the bit-skip. The decoding device and method of decoding are particularly simple and may be applied in devices, e.g. in a beam modulator array comprising a plurality of decoding devices, and/or in a lithography system comprising such a beam modulator array, in which space and computational resources are scarce while still providing a synchronization capability.