Multi-Phase Clock Switching with Stepwise Glitch-Free Transitions
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Solution Overview
Problem
Direct switching between multiple phase clocks can cause glitches and abrupt timing changes, which are problematic in systems requiring calibration and maximum timing margin, such as in memory chips.
Innovation Solution
The method involves step-by-step switching between adjacent phases using D-type flip-flops and logic gates, with a switch controller ensuring glitch-free transitions by employing a circular shift register to manage the phase changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If direct switching between clock phases is implemented, then switching speed is improved, but glitches and timing instability occur
Solution Approach 1:
The switching process is segmented into multiple intermediate steps rather than a single direct transition. The method divides the phase switching into a sequence of controlled transitions through intermediate phases, where each transition is managed by individual switch controllers that activate switches sequentially. This segmentation allows the system to achieve phase switching while maintaining timing stability and avoiding glitches that would occur with direct switching.
2Reliability
If step-by-step switching between adjacent phases is implemented, then timing stability is improved, but switching time increases
Solution Approach 1:
The switch controllers are pre-configured with the sequence of phase transitions before switching begins. The system prepares the switching sequence in advance, and the controllers execute the pre-planned transitions efficiently. This preliminary preparation allows the multi-step switching process to proceed rapidly without unnecessary delays, balancing timing stability with acceptable switching time.
3Reliability
If multiple switches and controllers are used for phase switching, then glitch-free operation is achieved, but device complexity increases
Solution Approach 1:
The switch controllers are designed as multi-functional units that can manage multiple phases and perform multiple operations. Each controller handles phase selection, switch activation, and timing coordination for its assigned phases. This universal design reduces the overall system complexity by consolidating control functions into versatile controllers rather than requiring dedicated simple switches for each phase transition.
Data Source
AI summary
A method and apparatus for glitch-free switching of multiple phase clock have been disclosed where switching from one phase to another phase is done step-by-step to avoid generating a glitch.