Dual-Loop Delay-Locked Clock Output Phase Adjustment
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Solution Overview
Problem
Delay-locked loops (DLLs) in integrated circuits face challenges in quickly and effectively adjusting to voltage, temperature, and process variations, leading to inadequate phase-lock of output clock signals due to limited error signal range and response speed.
Innovation Solution
A dual feedback loop system is implemented in the DLL, where the first feedback loop generates a feedback signal for phase difference adjustments and a second feedback loop generates a regulated signal to control a resistor-capacitor network, enabling both loops to compensate for temperature and voltage variations across different frequency ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single feedback loop is used in the delay-locked loop, then the device complexity is reduced, but the response speed to voltage and temperature variations is insufficient and the phase-lock accuracy deteriorates
Solution Approach 1:
The single feedback loop is segmented into two independent feedback loops: a first feedback loop that responds quickly to high-frequency variations with less filtering, and a second feedback loop that compensates for low-frequency variations with higher filtering. This segmentation allows each loop to be optimized for different frequency ranges, improving overall response speed without excessive complexity
Solution Approach 2:
The solution adds a frequency dimension to the feedback control by implementing loops with different filtering characteristics. The first loop has minimal filtering for fast response to high-frequency changes, while the second loop has stronger filtering for stable compensation of low-frequency drifts, creating a multi-dimensional approach to phase adjustment
2Stability of the object's composition
If a single feedback loop with high filtering is used, then the stability against low-frequency variations is improved, but the response speed to high-frequency variations deteriorates
Solution Approach 1:
The feedback control is segmented into two loops with different filtering strengths. The second feedback loop incorporates higher filtering to provide stable compensation for low-frequency variations, while the first feedback loop uses less filtering to maintain fast response to high-frequency variations, resolving the trade-off between stability and speed
Solution Approach 2:
The system dynamically assigns different filtering characteristics to different feedback loops based on the frequency characteristics of the variations they are designed to handle. This dynamic approach allows the system to simultaneously achieve fast response and high stability by adapting the filtering level to the specific feedback path
3Device complexity
If the error signal range is limited, then the device complexity is reduced, but the ability to compensate for voltage, temperature, and process variations deteriorates
Solution Approach 1:
The solution expands the compensation capability by adding a second feedback dimension with higher low-frequency gain. This additional dimension allows the system to cover a wider range of variations including both high-frequency and low-frequency changes, increasing adaptability without significantly increasing overall complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This dual feedback loop system enhances the DLL's responsiveness to variations, providing a wider frequency and delay range, making it more robust to both low-frequency and high-frequency variations, and ensuring faster response times compared to single-loop systems.
Implementation Method 1
The chain of delay elements forms a resistor-capacitor network in the variable delay circuit. The feedback signal controls a capacitance of the resistor-capacitor network, and the regulated signal controls a resistance of the resistor-capacitor network.
Data Source
AI summary
A delay-lock loop includes two feedback loops for controlling delay elements in the delay-lock loop. The first feedback loop includes a feedback circuit for generating a feedback signal indicating a delay adjustment based on a phase difference between an input clock signal to the delay-locked loop and an output clock signal generated by the delay-locked loop. The second feedback loop includes a power regulator that generates a regulated signal by regulating a power supply using the feedback signal as a reference. The delay-lock loop further includes a variable delay circuit including a resistor-capacitor network. The variable delay circuit controls a capacitance in the resistor-capacitor network based on the feedback signal and controls a resistance of the resistor-capacitor network based on the regulated signal. In this way, variable delay circuit generates the output clock signal by delaying the input clock signal based on both the feedback signal and the regulated signal.