Clock Signal Calibration Using Delayed Edge Selection
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Solution Overview
Problem
Conventional clock signal calibration methods in microcontrollers and ICs face challenges such as increased power consumption, longer calibration times, and reduced continuity of service due to initial phase errors and synchronization errors, especially in IoT applications where precision and accuracy are critical.
Innovation Solution
A calibration system that includes an input node for the clock signal, a reference node, a delay line to produce delayed clock replicas, and a calibration block to provide an error signal for frequency compensation, allowing for accurate alignment of the clock signal with the reference clock, reducing calibration time, and improving continuity of service.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional clock calibration methods are used to compensate for phase errors, then measurement precision is improved, but calibration time increases and continuity of service is reduced
Solution Approach 1:
The patent applies preliminary action by performing multiple clock cycle measurements during an initial calibration phase to establish a baseline relationship between the reference clock and the clock signal. This preliminary characterization of the system allows for faster subsequent calibrations, as the measurement patterns and error characteristics are pre-established, reducing the time needed for accurate calibration in operation.
Solution Approach 2:
The patent implements feedback by continuously monitoring the relationship between the reference clock and the clock signal, measuring phase differences and frequency ratios, and using this information to dynamically adjust calibration parameters. The system feeds back calibration results to refine future measurements, allowing for reduced calibration time while maintaining precision through adaptive correction based on observed deviations.
2Measurement precision
If observation time is increased to reduce phase error effects, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The patent applies partial action by performing a limited number of clock cycle measurements (e.g., measuring N cycles of the clock signal against M cycles of the reference clock) rather than continuously monitoring for extended periods. This partial measurement approach achieves sufficient calibration accuracy for IoT applications while significantly reducing the power consumption associated with prolonged calibration operations.
Solution Approach 2:
The patent changes parameters by dynamically adjusting the number of clock cycles measured and the observation window based on calibration needs. Instead of using a fixed long observation time, the system adapts the measurement parameters to achieve the required precision with minimal power consumption, balancing accuracy requirements against energy constraints in battery-powered IoT devices.
3Measurement precision
If conventional calibration procedures are implemented to ensure clock accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by designing a calibration system that can operate with different types of reference clocks (external crystal oscillators, RC oscillators, or other frequency sources) and adapt to various clock signal frequencies. The same calibration methodology and measurement approach work across different device configurations and reference sources, reducing the need for separate calibration circuits for each scenario and simplifying the overall device architecture.
Solution Approach 2:
The patent implements self-service by enabling the calibration system to automatically characterize its own timing relationships without requiring external calibration equipment or complex test setups. The microcontroller uses its own internal resources (timers, counters, and existing clock circuits) to perform self-calibration, eliminating the need for additional external calibration hardware and reducing system complexity while maintaining measurement precision.
Data Source
AI summary
In accordance with an embodiment, a method includes: producing a set of delayed replicas of a reference clock signal, wherein delayed replicas in the set of delayed replicas have respective signal edges delayed in time by a mutual time delay therebetween; producing a set of edge detecting signals comprising edge detecting signals indicative of respective distances of edges of delayed replicas in the set of delayed replicas from an edge of a clock signal having a clock period; selecting based on edge detecting signals in the set of edge detecting signals a delayed replica in the set of delayed replicas having a distance from the clock signal edge that is shorter than the distance from the clock signal edge of any other delayed replica in the set of delayed replicas.