DLL Local Coarse Delay Units for Low-Jitter Clock Shifting
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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 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, ..., DUN) that can be individually switched in and out of the signal path. This segmentation allows the system to achieve coarse delay adjustment by selectively enabling different segments without requiring high-power remote switching, as each segment operates independently with lower power requirements.
Solution Approach 2:
The delay units are pre-configured and positioned within the delay line system before operation. The switching mechanism is pre-established to enable rapid transitions between delay configurations without requiring high-power remote activation. This preliminary arrangement allows the system to switch between delay states efficiently with minimal power consumption and jitter.
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:
By dividing the delay line into multiple smaller delay units rather than using a single remote-controlled coarse delay unit, the system achieves delay variability through incremental switching of segments. This segmentation reduces the instantaneous current draw and voltage variations associated with remote coarse-shifting, thereby minimizing jitter and maintaining signal synchronization stability.
Solution Approach 2:
Each delay unit in the segmented delay line is designed with local switching capability, allowing independent control of each segment. This local quality approach enables fine-grained delay adjustment without the need for high-power remote switching, reducing voltage fluctuations and maintaining reliable signal synchronization throughout the system.
3Adaptability or versatility
If remote coarse-shifting is implemented to adjust delay, then time delay can be changed, but instantaneous current draw reaches one milli-amp
Solution Approach 1:
The delay adjustment functionality is divided into multiple smaller delay units that can be switched incrementally. Instead of requiring one milli-amp of instantaneous current to activate a single remote coarse delay unit, the system uses multiple low-power segments that can be activated sequentially or in combination, achieving the same total delay range with significantly reduced instantaneous current draw from each switching event.
Data Source
AI summary
One delay locked loop circuit embodiment includes a delay line system configured to generate a clock output signal by adding a delay line system time delay to a clock reference signal, a phase detector, a shift register, and a control unit. The delay line system includes a coarse delay line to adjust the delay line system time delay by remote coarse-shifting, a phase selector configured to adjust the delay line system time delay by local coarse-shifting output signals from a series of local coarse delay units, and a phase mixer to adjust a particular time delay of the clock output signal by fine-shifting. The phase mixer does not receive the clock reference signal. The phase detector detects a phase difference between the clock reference signal and the clock output signal. The shift register controls the remote coarse-shifting, and the control unit controls the local coarse-shifting, based on the phase difference.