Clock Edge Alignment Detection Across Mixed-Frequency Domains
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Solution Overview
Problem
Existing methods for detecting the relative positioning of clock signals with different frequencies, such as sampling one clock with another, lead to stability issues and complicate clock domain management, especially when the frequency ratio is not straightforward.
Innovation Solution
Generating a phase logic signal that indicates the alignment of rising edges between a fast and a slow clock signal, using flip-flops and EXCLUSIVE OR logic gates to create an auxiliary signal independent of the clock signals, allowing for precise alignment detection regardless of frequency ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one clock signal is sampled with the aid of another clock signal, then it is possible to know during which cycle the change of level occurs, but stability problems arise because one clock signal is sampled with the aid of a signal of another clock
Solution Approach 1:
The patent introduces an intermediary circuit comprising sequential elements (flip-flops) and logic gates that act as a mediator between the first and second clock domains. This intermediary processes the clock signals through a standardized interface, preventing direct sampling issues while maintaining detection precision. The sequential elements buffer and condition the signals, ensuring stable operation across clock domain boundaries.
2Measurement precision
If one clock signal is sampled with the aid of another clock signal, then relative positioning information can be obtained, but the management of the clock domain becomes greatly complicated
Solution Approach 1:
The patent segments the clock domain management function into distinct modular components: sequential elements for timing capture, logic gates for position detection, and separate input/output interfaces for each clock domain. This segmentation isolates the detection logic from the clock sources, simplifying management by allowing each component to operate independently with well-defined interfaces.
Solution Approach 2:
The detection circuit is designed as a universal interface that can handle multiple clock frequency ratios (where the second clock frequency is an integer multiple of the first). The same circuit topology works for any integer multiple relationship, eliminating the need for specialized management logic for each frequency ratio and greatly simplifying clock domain management.
3Productivity
If data transmission is performed without precise clock alignment, then transmission speed may be increased, but data loss risks increase
Solution Approach 1:
The patent performs preliminary detection of the relative positioning between clock edges before data transmission occurs. The detection circuit pre-characterizes the timing relationship between clock domains, allowing the system to establish optimal transmission windows in advance. This preliminary knowledge enables high-speed transmission while maintaining reliability by avoiding data loss-prone timing conditions.
Data Source
AI summary
A device is for detecting a relative positioning of two clock signals including a fast clock signal and a slow clock signal. The fast clock frequency may be n times greater than a slow clock frequency, and n includes an integer greater than 1. The device includes a phase logic signal generator for generating a phase logic signal from the two clock signals by assigning a predetermined logic value to the phase logic signal when a rising edge of the fast clock signal matches a predetermined location of the slow clock signal.