Delay Line Calibration Mechanism for Online Multi-Clock Jitter Control
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Solution Overview
Problem
Existing delay line calibration mechanisms face challenges with mismatch between calibrated and replica delay lines, leading to significant jitter and increased circuit area and power consumption, and require offline calibration, which is not self-adjusting to environmental changes.
Innovation Solution
A delay line calibration mechanism comprising a delay line, a controller, and a phase detector that generates input and calibration pulses, and delay selection signals to compare and adjust the delay periods, allowing for online calibration and reducing complexity, circuit area, and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a replica delay line is utilized for calibration, then the delay line can be calibrated, but mismatch between calibrated and replica delay lines generates large jitter and increases circuit area and power consumption
Solution Approach 1:
The patent uses a single delay line that serves both as the calibrated delay line and the replica delay line. Instead of creating a separate replica delay line copy, the system calibrates the delay line in-place by comparing its output phase with a reference clock phase, thereby eliminating the need for additional replica circuitry while maintaining calibration precision
Solution Approach 2:
The delay line is designed to perform multiple functions: it acts as both the calibrated delay line providing delayed clock signals and the replica delay line used for calibration. This multi-functionality eliminates the need for separate replica delay line circuits, reducing overall circuit area while maintaining calibration capability
2Measurement precision
If a replica delay line is utilized for calibration, then the delay line can be calibrated, but power consumption increases
Solution Approach 1:
The delay line performs dual functions as both the operational delay line and the calibration replica, eliminating the need for separate replica delay line circuits. This consolidation reduces the total number of active components and their associated power consumption while maintaining calibration precision
Solution Approach 2:
Instead of powering a separate replica delay line for calibration, the system uses the same delay line structure for both calibration and operation, thereby halving the power consumption related to delay line operation while maintaining calibration precision
3Manufacturing precision
If delay lines are designed to provide precise delay, then delay precision is improved, but delay variation under changing environmental conditions affects system reliability
Solution Approach 1:
The patent implements a feedback mechanism where a phase detector continuously compares the phase of the delay line output with a reference clock, and a delay control circuit adjusts the delay amount based on the detected phase difference. This closed-loop feedback system compensates for environmental variations in real-time, maintaining delay precision and system reliability under changing temperature, voltage, and process conditions
Solution Approach 2:
The delay line is designed with dynamic adjustability, allowing the delay amount to be modified in real-time based on environmental conditions. The delay control circuit dynamically adjusts the delay elements within the delay line to maintain precise delay despite variations in temperature, supply voltage, process, and age
4Measurement precision
If delay lines require offline calibration, then calibration can be performed, but the system must be taken offline and cannot adapt to environmental changes during operation
Solution Approach 1:
The patent enables continuous calibration during normal system operation. The phase detector and delay control circuit operate concurrently with the delay line's primary function, allowing the system to maintain precise delay calibration without interruption. This continuous calibration adapts to environmental changes in real-time while the system remains fully operational
Solution Approach 2:
The system performs preliminary calibration adjustments continuously in the background during normal operation, rather than requiring scheduled offline calibration events. The feedback mechanism proactively compensates for drift before it affects system performance, maintaining availability while ensuring precision
Data Source
AI summary
A delay line calibration mechanism includes a delay line, a phase detector, and a controller. The delay line receives an input pulse, a calibration pulse, a first delay selection signal, and a second delay selection signal, delays the input pulse for a delay period according to the first delay selection signal to output a delayed pulse, and delays the calibration pulse for a calibration delay period according to the second delay selection signal to output a delayed calibration pulse. The controller is for generating the input pulse, the calibration pulse, and a reference pulse. The controller also generates the first delay selection signal, and generates the second delay selection signal according to a phase difference signal. The phase detector is for generating the phase difference signal indicating the difference between the delayed calibration pulse and the reference pulse by comparing the delayed calibration pulse and the reference pulse.