Sleep-Mode Radio Clocking with Calibrated Low-Power Oscillators
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Solution Overview
Problem
Current oscillator technologies face challenges in reducing power consumption during sleep mode in radios, where maintaining accuracy is crucial to minimize unnecessary wake-ups and associated high power consumption.
Innovation Solution
Implementing a low power, less accurate oscillator during sleep mode, calibrated by a high frequency, accurate oscillator, and utilizing techniques such as mistuning crystal oscillators and reducing load capacitance to minimize power usage while ensuring accurate timekeeping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high accuracy oscillator is used during sleep mode, then timekeeping accuracy is improved, but power consumption increases
Solution Approach 1:
The system dynamically switches between two oscillator configurations based on operational mode. During sleep mode, it uses a low-power RC oscillator with reduced accuracy. During active mode, it switches to a high-accuracy crystal oscillator. This dynamic adaptation resolves the contradiction by allowing the system to accept reduced accuracy during sleep in exchange for dramatically lower power consumption, then restore full accuracy when power is available.
Solution Approach 2:
The oscillator system is segmented into two distinct parts: a low-power RC oscillator for sleep mode operation and a high-accuracy crystal oscillator for active mode. Each segment is optimized for its specific operational context. The RC oscillator consumes minimal power during sleep, while the crystal oscillator provides necessary accuracy during active communication, resolving the accuracy-power tradeoff through functional segmentation.
2Use of energy by moving object
If a low power oscillator is used during sleep mode, then power consumption is reduced, but timekeeping accuracy deteriorates
Solution Approach 1:
The system performs preliminary calibration of the low-power RC oscillator using the high-accuracy crystal oscillator before entering sleep mode. This preliminary action compensates for the inherent inaccuracy of the RC oscillator, allowing it to maintain acceptable timekeeping accuracy during sleep mode while consuming minimal power. The calibration data is stored and used to adjust the RC oscillator's frequency, resolving the accuracy-deficit of low-power oscillators.
Solution Approach 2:
The system implements a feedback mechanism where the high-accuracy crystal oscillator periodically calibrates the low-power RC oscillator. During active mode, the crystal oscillator measures the drift of the RC oscillator and applies correction factors. This feedback loop ensures that even though the RC oscillator is inherently less accurate, its timekeeping remains sufficiently precise for sleep mode operation while maintaining low power consumption.
3Measurement precision
If the system wakes up frequently to maintain accuracy, then timekeeping accuracy is improved, but average power consumption increases
Solution Approach 1:
The system performs preliminary calibration of the RC oscillator using the crystal oscillator before entering sleep mode, and potentially mid-sleep calibration events. This preliminary action establishes accurate timing parameters that allow the RC oscillator to run autonomously during sleep without frequent wake-ups. By preparing the RC oscillator in advance with accurate calibration data, the system maintains timekeeping accuracy while minimizing wake-up events and associated power consumption.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Significantly reduces power consumption during sleep mode without compromising accuracy, allowing for efficient low power clocking in radios, particularly in applications with extended sleep periods, by using a low power oscillator calibrated periodically with a high accuracy oscillator.
Implementation Method 1
In a crystal oscillator, a piezoelectric crystal (commonly quartz) may take the place of the filter to stabilize the frequency of oscillation. These kinds of oscillators contain quartz crystals that mechanically vibrate as resonators, and their vibration determines the oscillation frequency.
Implementation Method 2
These kinds of oscillators contain quartz crystals that mechanically vibrate as resonators, and their vibration determines the oscillation frequency.
Data Source
AI summary
Systems and methods of low power docking of sleep mode radios are disclosed herein. In an example embodiment, a crystal oscillator is purposefully mistuned to achieve lower power consumption, and then synchronized using a high frequency crystal oscillator. In an alternative embodiment, the input offset voltages of the comparator in an RC oscillator are cancelled, which allows low power operation and high accuracy performance when tuned to the high frequency crystal. A lower power comparator may be used with higher input offset voltages but still achieve higher accuracy. The RC circuit is switched back and forth on opposite phases of the output, cancelling the offset voltage on the inputs of the comparator.