Clock Phase Detector for Variable-Frequency Domain Synchronization
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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 high-resolution phase detector is employed to track frequency transients and determine the relative phase and period between clock domains, using delayed versions of clock signals to sample and synchronize signals with low latency, thereby reducing the need for asynchronous FIFOs and minimizing synchronization failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If asynchronous FIFOs are used to synchronize signals between clock domains with variable frequencies, then synchronization capability is provided, but area overhead and latency increase significantly
Solution Approach 1:
The patent extracts the essential synchronization function from complex asynchronous FIFO structures by using a phase detector that only monitors clock phase relationships. This selective extraction of the core synchronization need eliminates the need for large FIFO memory structures, reducing area overhead while maintaining synchronization capability for variable frequency clock domains.
Solution Approach 2:
The synchronization approach is segmented into separate functional blocks: a phase detector for monitoring clock relationships, a control unit for managing data transfer timing, and minimal buffer structures. This segmentation replaces the monolithic FIFO structure with distributed, smaller components that achieve the same synchronization goal with reduced total area.
2Adaptability or versatility
If asynchronous FIFOs are used to synchronize signals between clock domains, then synchronization is achieved, but latency increases due to multiple flip-flops for Gray-coded pointer synchronization
Solution Approach 1:
The patent removes the multi-cycle Gray-coded pointer synchronization mechanism from the data path by using a phase detector that directly monitors clock phase relationships. This extraction of the essential timing information eliminates the need for multiple synchronization flip-flops, reducing latency while maintaining synchronization capability.
Solution Approach 2:
The phase detector performs preliminary monitoring of clock phase relationships before data transfer occurs. By anticipating the timing relationships between clock domains in advance, the system can prepare synchronization control signals ahead of time, eliminating the need for multi-cycle pointer synchronization and reducing overall latency.
3Adaptability or versatility
If conventional synchronization techniques are used for variable frequency clocks, then synchronization is provided, but complexity increases
Solution Approach 1:
The phase detector is designed as a universal component that can handle both fixed and variable frequency clock domains through a single unified architecture. This multi-functional approach eliminates the need for separate synchronization circuits for different clock types, reducing design complexity while maintaining adaptability to various operating conditions.
Solution Approach 2:
The system adapts to variable frequency clocks by dynamically adjusting to changing phase relationships detected by the phase detector. Rather than using complex fixed-architecture synchronizers, the system changes its operational parameters (timing control signals) based on detected phase differences, simplifying the overall design while maintaining synchronization capability across frequency variations.
Data Source
AI summary
A method and a system are provided for clock phase detection. A first set of delayed versions of a first clock signal is generated and a second set of delayed versions of a second clock signal is generated. The second set of delayed versions of the second clock signal is sampled using the first set of delayed versions of the first clock signal to produce an array of clock samples in a domain corresponding to the first clock signal. At least one edge indication is located within the array of clock samples.