Periodic Clock Synchronizer for Variable-Frequency Domains
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Solution Overview
Problem
Conventional synchronization techniques fail to effectively synchronize signals between clock domains where at least one clock has a variable frequency, leading to increased complexity and area overhead, particularly due to the use of asynchronous FIFOs which incur latency and high probability of synchronization failure.
Innovation Solution
A method and system that utilize a high-resolution phase detector to compute phase and period values between two clock signals, allowing for low-latency synchronization by determining the relative phase and period between clock domains, even when clock frequencies vary, thereby eliminating the need for asynchronous FIFOs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asynchronous FIFOs are used to synchronize signals between clock domains with variable frequencies, then synchronization can be achieved, but area overhead and latency increase significantly
Solution Approach 1:
The patent extracts the essential synchronization function from the complex FIFO mechanism by using a phase detector to directly measure and compensate for clock phase differences. This removes the need for large FIFO buffers while maintaining synchronization reliability, thereby reducing area overhead significantly.
Solution Approach 2:
The patent replaces the mechanical FIFO buffer system with a computational phase detection and compensation system. Instead of using physical memory structures to handle timing differences, the system uses digital signal processing to predict and compensate for phase variations, achieving the same synchronization goal with much lower area cost.
2Reliability
If asynchronous FIFOs are used for clock domain synchronization, then signals can be transmitted across clock domains, but latency increases due to multiple flip-flop stages
Solution Approach 1:
The phase detector performs preliminary measurement of clock phase relationships in advance, allowing the system to predict future phase positions and pre-calculate compensation values. This preliminary action eliminates the need for multiple sequential flip-flop stages, thereby reducing synchronization latency while maintaining reliability.
3Reliability
If conventional synchronization methods are used with variable frequency clocks, then synchronization can be achieved, but device complexity increases
Solution Approach 1:
The patent changes the approach from tracking complex variable frequency relationships to measuring and compensating for phase differences directly. By focusing on phase as the key parameter rather than frequency relationships, the system simplifies the synchronization logic while maintaining reliability with variable frequency clocks.
4Device complexity
If periodic synchronizers are used with fixed frequency clocks, then synchronization is simpler with lower latency, but the system cannot handle variable frequency clocks
Solution Approach 1:
The patent introduces dynamic phase detection and extrapolation capabilities that allow the synchronizer to adapt to changing clock frequencies in real-time. The phase detector continuously measures phase relationships and updates compensation values dynamically, enabling the system to maintain the simplicity of periodic synchronization while handling variable frequency clocks.
Solution Approach 2:
The system uses feedback from the phase detector to continuously monitor and adjust for phase variations caused by frequency changes. This feedback mechanism allows the synchronizer to maintain accurate synchronization despite variable clock frequencies, combining the simplicity of periodic synchronization with the adaptability needed for frequency variations.
Data Source
AI summary
A method and a system are provided for variation-tolerant synchronization. A phase value representing a phase of a second clock signal relative to a first clock signal and a period value representing a relative period between the second clock signal and the first clock signal are received. An extrapolated phase value of the second clock signal relative to the first clock signal corresponding to a next transition of the first clock signal is computed based on the phase value and the period value.