FSM-Based Clock-Domain Synchronization With Lower Latency
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Solution Overview
Problem
Existing synchronization systems face challenges in minimizing latency when conveying synchronization information between clock domains, often requiring multiple flip-flops to prevent metastability and ensure predictable global behavior.
Innovation Solution
The system reduces latency by utilizing one of the flip-flops used for encoding the current state of a finite-state machine as a synchronization flip-flop, allowing for a single-bit difference between wait and next states, thereby reducing the number of flip-flops needed in the synchronization chain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple flip-flops are used in the synchronization chain to prevent metastability, then reliability is improved, but latency increases and device complexity increases
Solution Approach 1:
The patent merges the synchronization function with the state storage function by using the same flip-flop for both purposes. The state flip-flop simultaneously stores the finite state machine state and acts as the final synchronization stage for the control signal, eliminating the need for a separate synchronization chain and reducing latency while maintaining reliability
Solution Approach 2:
The state flip-flop is designed to perform multiple functions: storing the current state of the finite state machine and simultaneously serving as the synchronization flip-flop for the control signal. This multi-functionality reduces the total number of flip-flops needed and decreases synchronization latency
2Reliability
If multiple flip-flops are used in the synchronization chain, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent combines the synchronization circuit with the finite state machine by sharing the state flip-flop. This merging eliminates separate synchronization circuitry and reduces device complexity while maintaining synchronization reliability through the integrated design
Solution Approach 2:
The state flip-flop serves dual purposes as both state storage and synchronization element, reducing the overall device complexity by eliminating redundant components while maintaining reliable synchronization between clock domains
3Reliability
If more flip-flops are used for synchronization, then synchronization reliability is improved, but power consumption increases
Solution Approach 1:
By merging the synchronization function with the state storage function in the same flip-flop, the patent reduces the total number of active flip-flops in the synchronization path, thereby reducing dynamic power consumption while maintaining synchronization reliability
Solution Approach 2:
The multi-functional state flip-flop reduces the number of dedicated synchronization flip-flops, leading to lower overall power consumption in the synchronization system while ensuring reliable operation across clock domains
Data Source
AI summary
A system for synchronizing the operation of a circuit with a control signal includes synchronization flip-flops operating in cascade for receiving a control signal to be synchronized and providing a corresponding control signal synchronized with a clock signal, and a circuit including a finite state machine for receiving the clock signal having state flip-flops for storing the current state of the finite state machine, wherein a last synchronization flip-flop includes one of the state flip-flops.