System Clock Compensation Circuit for Delay-Accurate PLL Locking
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Solution Overview
Problem
Existing clock synchronization and frequency translation technologies face challenges in reducing system clock errors, minimizing clock propagation delay variation, and achieving precise timing distribution and recovery, especially under varying operating conditions such as temperature and vibration.
Innovation Solution
The integration of a system clock compensation circuit within integrated circuits (ICs) that utilizes error models to estimate and digitally compensate for system clock errors, combining closed-loop and open-loop estimates to generate compensation signals, and includes delay compensation circuits to adjust for signal path variations, thereby enhancing phase-locked loop performance and timing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If system clock generation circuit is used to generate clock signal based on reference signal, then clock synchronization is achieved, but system clock errors and timing inaccuracies occur under varying operating conditions
Solution Approach 1:
The patent applies preliminary action by pre-characterizing the system clock error across different operating conditions (temperature, voltage, frequency) and storing compensation values in lookup tables before actual operation. During runtime, the compensation circuit retrieves pre-calculated correction values based on current operating conditions, eliminating the need for real-time complex calculations and enabling fast compensation without adding computational burden during critical timing operations
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting compensation parameters based on detected operating conditions. The system monitors temperature, voltage, and frequency parameters, and automatically selects appropriate compensation values from lookup tables or adjusts PLL control parameters accordingly. This allows the system to adapt to varying environmental conditions and maintain timing accuracy across different operating states
2Loss of time
If clock propagation delay is minimized for fast timing, then latency is reduced, but variation in delay under different operating conditions increases
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting delay compensation based on operating conditions. The system characterizes propagation delay variations across temperature, voltage, and frequency ranges, and applies appropriate compensation values from lookup tables to maintain consistent timing. This allows the system to achieve fast timing while compensating for environmental variations that would otherwise cause delay inconsistencies
3Speed
If phase-locked loop update rate is increased for faster locking, then locking speed improves, but timing precision and stability decrease
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing optimal PLL control parameters and compensation values for different operating conditions. The system uses lookup tables containing pre-characterized phase detection corrections and PLL tuning parameters, allowing fast retrieval during operation without requiring complex real-time calculations that would compromise precision or require excessive update cycles
4Measurement precision
If reference signal monitoring precision is improved for accurate phase detection, then timing accuracy increases, but monitoring latency increases
Solution Approach 1:
The patent applies preliminary action by pre-characterizing phase detection errors and storing correction values in lookup tables based on operating conditions. The reference monitoring circuit uses these pre-calculated compensation values to quickly correct phase detection results without requiring extended monitoring periods or complex real-time analysis, thereby maintaining high precision while minimizing latency
Data Source
AI summary
Apparatus and methods for clock synchronization and frequency translation are provided herein. Clock synchronization and frequency translation integrated circuits (ICs) generate one or more output clock signals having a controlled timing relationship with respect to one or more reference signals. The teachings herein provide a number of improvements to clock synchronization and frequency translation ICs, including, but not limited to, reduction of system clock error, reduced variation in clock propagation delay, lower latency monitoring of reference signals, precision timing distribution and recovery, extrapolation of timing events for enhanced phase-locked loop (PLL) update rate, fast PLL locking, improved reference signal phase shift detection, enhanced phase offset detection between reference signals, and/or alignment to phase information lost in decimation.