Clock Domain Synchronization Using State Variables and Acquisition Curves
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Solution Overview
Problem
Existing synchronization techniques for clock signals in integrated circuits often result in nonlinear or unpredictable behavior, leading to undesirable transients in audio signals and erratic data transport in cascaded circuits.
Innovation Solution
A synchronization circuit that determines state-variable differences between clock signals, generates a synchronization acquisition curve based on temporal history, and sums these differences to synchronize clock signals without discontinuous transients, ensuring continuous phase and frequency alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing synchronization techniques (phase-locked loop) are used to synchronize clock signals in different timing domains, then the clock signals can be locked, but the frequency and phase exhibit nonlinear or unpredictable variations during synchronization
Solution Approach 1:
The patent pre-calculates a synchronization acquisition curve before actual synchronization occurs. This curve represents the desired temporal trajectory for phase and frequency differences during lock acquisition. By having this reference trajectory prepared in advance, the system can guide the synchronization process to follow a predictable, continuous path rather than allowing nonlinear variations.
Solution Approach 2:
The patent implements a feedback mechanism that continuously monitors actual phase and frequency differences between clock signals and compares them against the pre-calculated synchronization acquisition curve. This feedback enables real-time adjustment to ensure the actual synchronization trajectory matches the desired continuous path, eliminating unpredictable variations.
Solution Approach 3:
The patent transforms the synchronization problem from directly controlling phase and frequency to controlling state-variable differences (such as phase difference and frequency difference) that are then mapped through the synchronization acquisition curve. This parameter transformation enables predictable temporal behavior by changing how the synchronization process is governed.
2Reliability
If clock signals are synchronized using conventional methods, then frequency and phase lock is achieved, but discontinuous transients occur in state variables affecting audio and data transport
Solution Approach 1:
The synchronization acquisition curve is pre-calculated to define the ideal temporal evolution of phase and frequency differences during lock acquisition. This preliminary planning ensures that the synchronization process follows a continuous trajectory that avoids abrupt changes, thereby preventing transient distortions in audio and data transport before they can occur.
Solution Approach 2:
The patent introduces the synchronization acquisition curve as an intermediary reference that mediates between the master and slave clock signals. Instead of directly locking the slave clock to the master clock (which causes discontinuous transients), the synchronization acquisition curve serves as an intermediate guide that ensures continuous, smooth transitions in all state variables.
3Reliability
If phase and frequency of clock signals are locked using existing techniques, then synchronization is achieved, but the behavior is nonlinear and unpredictable over time
Solution Approach 1:
The synchronization acquisition curve is computed in advance based on the desired temporal behavior. This pre-computation provides a known, predictable reference trajectory that defines exactly how phase and frequency differences should evolve over time during synchronization, making the process predictable and measurable rather than nonlinear and unpredictable.
Solution Approach 2:
The patent changes the control parameters from directly managing phase and frequency to managing state-variable differences that are constrained to follow the pre-calculated synchronization acquisition curve. This parameter transformation converts an unpredictable nonlinear process into a predictable, measurable trajectory.
Data Source
AI summary
Embodiments of a synchronization circuit, a method for synchronizing clock signals, and electronic devices that include the synchronization circuit or a computer-program product (e.g., software) with instructions for operations in the method are described. This synchronization circuit synchronizes clock signals in different timing domains using state variables. In particular, the synchronization circuit generates a synchronization acquisition curve based on a temporal history of state-variable differences between the clock signals. Next, the synchronization circuit synchronizes the clock signals (without a discontinuous temporal transient in one or more state variables of a dependent one of the clock signals) based on the sum of the synchronization acquisition curve and the state-variable differences between the clock signals. This state variable may include: a phase of the dependent clock signal, a frequency of the dependent clock signal, and/or a rate of change of the frequency of the dependent clock signal.