Delay-Locked Loop Calibration for External Feedback Delay
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Solution Overview
Problem
Delay locked loops (DLLs) face challenges in operating over a full range of constraints due to uncompensated external delays, leading to design trade-offs and increased laboratory efforts for characterization and testing.
Innovation Solution
The implementation of a DLL with a delay compensation circuit that measures and adjusts the controllable delay line to compensate for external delays, allowing the DLL to operate robustly across various conditions and reducing the need for extensive characterization and testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If external delay is not compensated, then the DLL structure remains simple, but the DLL cannot operate over a full range of operating constraints and suffers from extensive design constraints
Solution Approach 1:
The delay compensation circuit performs preliminary measurement and compensation of external delay before the DLL operates. The circuit measures the external delay through the feedback path and adjusts the controllable delay line in advance to compensate for this delay, enabling the DLL to operate correctly without requiring complex redesign for different operating conditions.
2Ease of manufacture
If external delay is not compensated, then the device complexity remains low, but extensive laboratory efforts for characterization and evaluation are required
Solution Approach 1:
The delay compensation circuit performs self-measurement and self-adjustment of the external delay. The circuit automatically measures the delay through the feedback path and compensates for it without requiring external laboratory equipment or manual characterization, thereby eliminating extensive laboratory efforts while maintaining relatively simple circuit structure.
3Reliability
If the feedback clock signal delay is not compensated, then the design constraints are reduced, but the DLL performance deteriorates under varying operating conditions
Solution Approach 1:
The delay compensation circuit uses feedback from the feedback clock signal path to measure and compensate for external delay. The circuit continuously monitors the delay through the feedback path and adjusts the controllable delay line accordingly, ensuring reliable DLL performance under varying operating conditions while keeping the compensation mechanism relatively simple.
Data Source
AI summary
Provided herein are delay locked loops (DLLs) with calibration for external delay. In certain embodiments, a timing alignment system includes a DLL including a detector that generates a delay control signal based on comparing a reference clock signal to a feedback clock signal, and a controllable delay line configured to generate the feedback clock signal by delaying the reference clock signal based on the delay control signal. The timing alignment system further includes a delay compensation circuit that provides an adjustment to the controllable delay line to compensate for a delay of the feedback clock signal in reaching the detector.