Phase-Locked Loop Dead Zone Switching for Faster Re-Lock
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Solution Overview
Problem
Existing phase-locked loop devices face issues such as a narrow linear range of sampling phase detectors, loss of lock, and long phase lock times due to interference, which is exacerbated by the need for dead-band control in frequency-locked loops.
Innovation Solution
A phase-locked loop device is designed with a frequency-locked loop circuit and a phase-locked loop circuit, incorporating a delay generator circuit, a frequency-phase detector with dead zone control, a charge pump circuit, a loop filter, a voltage-controlled oscillator, and a frequency divider. This configuration allows for automatic switching of the dead zone on/off, optimizing locking time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a frequency-locked loop with dead-band control is used to lock the output frequency, then the output frequency can be stabilized at N times the reference frequency, but when interference occurs the phase exceeds the linear range and the device loses lock, requiring long phase accumulation time to re-lock
Solution Approach 1:
The dead zone control mechanism dynamically adjusts the dead zone range based on the locking state. When locked, a first dead zone range is applied; when loss of lock is detected, a second dead zone range (smaller than the first) is applied to accelerate re-locking. This dynamic adjustment resolves the contradiction by adapting the dead zone to current operational needs.
Solution Approach 2:
The system continuously monitors the locking state through phase detection and feedback control. The frequency-phase detector provides feedback about whether the VCO is in lock, which triggers the dead zone control mechanism to adjust the dead zone range accordingly, enabling automatic recovery from loss of lock condition.
2Reliability
If a larger dead zone range is used to prevent loss of lock, then lock stability improves, but the linear range of the phase detector becomes narrower and re-locking time increases
Solution Approach 1:
The dead zone control mechanism switches between two dead zone ranges based on locking state. The first dead zone range (larger) maintains stability during normal operation, while the second dead zone range (smaller) enables faster re-locking when interference occurs, thus dynamically optimizing both stability and locking speed.
Solution Approach 2:
The system changes the dead zone parameter according to the locking state. When locked, a larger dead zone parameter is used for stability; when loss of lock occurs, the dead zone parameter is reduced to expand the linear range and accelerate re-locking, thus optimizing both stability and locking speed under different conditions.
3Reliability
If the dead zone is always on to maintain stability, then lock reliability improves, but the phase detector cannot respond quickly to phase changes and re-locking time increases
Solution Approach 1:
The dead zone control mechanism dynamically switches the dead zone state based on locking condition. During normal locked operation, the dead zone is configured for stability; upon detecting loss of lock, it transitions to a configuration that prioritizes rapid re-locking, thus resolving the contradiction between stability and response time.
Solution Approach 2:
The system periodically monitors the locking state and adjusts the dead zone configuration accordingly. This periodic detection and adjustment ensures that the dead zone is optimized for stability during lock and for rapid re-locking when interference occurs, balancing both requirements over time.
Data Source
AI summary
Disclosed is a phase-locked loop device. The phase-locked loop device includes a frequency-locked loop circuit and a phase-locked loop circuit. The frequency-locked loop circuit includes a delay generator circuit and a frequency-phase detector. The delay generator circuit generates a ramp signal based on the feedback clock signal, and compares the ramp signal with multiple reference voltages to generate multiple delayed feedback clock signals. The frequency-phase detector has a dead zone control mechanism that generates a locking signal based on phases of the reference clock signal and delayed feedback clock signal and automatically switches on/off the dead zone. The phase-locked loop circuit generates the first output current according to the phase difference between the reference clock signal and the feedback clock signal.