Local Coarse Delay Units for Low-Jitter DLL Clock Synchronization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Remote coarse-shifting in delay locked loops (DLLs) consumes significant power, causing jitter in delayed electrical signals and disrupting synchronization in integrated circuits, due to high instantaneous current draw and voltage variations on the power supply.
Innovation Solution
Implementing local coarse-shifting using external local coarse delay units (LCDUs) instead of remote coarse-shifting, which reduces power consumption and minimizes jitter by varying time delays within the DLL system without remote coarse-shifting, thereby maintaining stable signal synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If remote coarse-shifting is used to adjust time delays in a DLL system, then the time delay can be varied, but significant power is consumed and jitter is introduced in the delayed electrical signal
Solution Approach 1:
The delay line system is segmented into multiple independent delay units (DU1, DU2, DU3, DU4) that can be individually controlled. Instead of remotely shifting entire coarse delay lines, the system locally enables or disables individual delay units near the phase detector, allowing fine-grained time delay adjustment with minimal power consumption and no jitter introduction.
Solution Approach 2:
The patent introduces local delay units positioned between the remote coarse delay line and the phase detector as intermediaries. These local delay units act as mediators that can adjust the signal path locally without requiring remote switching operations, thereby eliminating the harmful effects of remote coarse-shifting while maintaining time delay adjustability.
2Adaptability or versatility
If remote coarse-shifting is used to vary time delays, then delay adjustment is achieved, but voltage variations on the power supply occur causing jitter
Solution Approach 1:
The patent applies local quality by positioning delay units with specific properties (local coarse delay units) at strategic locations near the phase detector rather than using uniform remote delay lines. These locally-placed units have different characteristics from remote units, providing stable, jitter-free delay adjustment that maintains power supply voltage stability and signal synchronization reliability.
Solution Approach 2:
The system performs preliminary delay adjustment using local delay units before the signal reaches the phase detector. By pre-adjusting the delay locally rather than remotely shifting after the fact, the system avoids introducing jitter and voltage variations that would compromise synchronization stability.
3Adaptability or versatility
If remote coarse-shifting is performed to adjust delay, then time delay can be changed, but instantaneous current draw increases significantly
Solution Approach 1:
The patent implements dynamic delay adjustment by enabling or disabling individual delay units through control signals (e.g., ENB1, ENB2) rather than performing static remote switching operations. This dynamic local control allows the system to adjust delay range adaptively while maintaining low instantaneous current draw, as only the necessary local delay units are activated rather than performing full remote coarse-shifting.
Data Source
AI summary
Methods, circuits, devices, and systems are provided, including embodiments with local coarse delay units. One embodiment includes generating a first delayed signal, a second delayed signal, and a third delayed signal by delaying a clock reference signal with various time delays of a coarse delay line and local coarse delay units. This method embodiment also includes generating a clock output signal based on the first delayed signal, the second delayed signal, or the third delayed signal, depending on a phase difference between the clock reference signal and the clock output signal.