Delay-Locked Loop Re-Locking Using Stored Control Voltage
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Solution Overview
Problem
Existing delay-locked loop (DLL) circuits take a considerable amount of time to re-lock after being affected by electrostatic discharge (ESD) or external noise, leading to undesirable data output in devices like DDI chips, as the control signal voltage deviates from the normal operation domain, requiring several dozens of microseconds to return to the normal state.
Innovation Solution
A DLL circuit apparatus and method that includes a storage to store a reference voltage value for the control signal voltage, a lock detector to determine the unlocking state, and an initializer to reset the control signal voltage to this reference value, allowing for quick recovery and re-locking by changing the setting of the charge pump.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DLL circuit performs conventional re-locking after ESD or noise interference, then the control signal voltage returns to normal operation domain, but the locking time takes several dozens of microseconds
Solution Approach 1:
The patent stores the initial locked state voltage value of the control signal in advance before any interference occurs. When ESD or noise causes unlocking, the system directly restores to this pre-stored voltage value instead of performing time-consuming conventional re-locking procedures, thereby significantly reducing the re-locking time while maintaining reliability
Solution Approach 2:
The patent employs a lock detector that continuously monitors whether the DLL is in a locked or unlocked state. When unlocking is detected due to ESD or noise, the system provides feedback to restore the control signal voltage to the stored initial locked state value, enabling automatic recovery without manual intervention and ensuring reliable operation
2Reliability
If the control signal voltage deviates from normal operation domain due to ESD or external noise, then DLL locking is disrupted, but recovery takes considerable time
Solution Approach 1:
The system pre-stores the correct locked state voltage value in a storage element before interference occurs. When ESD or noise disrupts operation, this pre-stored value enables immediate restoration of proper voltage levels, preventing prolonged operational disruption and maintaining productivity
Solution Approach 2:
By storing the initial locked state voltage value in advance, the system prepares a corrective action that can be immediately applied when interference occurs. This preliminary preparation counteracts the disruptive effect of ESD or noise before it can cause extended operational failures, thereby maintaining both reliability and productivity
Data Source
AI summary
A DLL circuit apparatus and a DLL locking method are provided. A control signal voltage value corresponding to a DLL locking state is stored, and a DLL unlocking state is detected when a change in control signal voltage value or a phase difference of clock signals occurs. When the DLL unlocking occurs, the DLL is locked again using the stored control signal voltage value. Accordingly, DLL unlocking from DLL locking state is quickly detected, and a fast DLL locking time occurs.