Wireless Sleep Timing Calibration for Low-Power RC Oscillators
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Solution Overview
Problem
Wireless communication devices face power consumption issues due to clock drifting in low power RC oscillator clocks, especially during long sleep periods, leading to inaccurate timing and increased battery drain.
Innovation Solution
Implement a sleep time management algorithm that performs calibration operations between long sleep durations, adjusting sleep times based on current and updated remaining times to minimize power consumption and maintain accuracy, using a high-accuracy clock for calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the wireless communication device enters power management mode for long sleep periods, then power consumption is reduced, but clock accuracy degrades due to RC oscillator drifting
Solution Approach 1:
The patent segments a long sleep period into multiple shorter intervals by inserting periodic wake-up events. Instead of one continuous long sleep, the device wakes up at predetermined intervals to perform calibration operations on the RC oscillator, then returns to sleep. This segmentation maintains clock accuracy by recalibrating the oscillator periodically while still achieving significant power savings through the predominantly sleeping state.
Solution Approach 2:
The patent performs calibration operations during brief wake-up periods before the device returns to deep sleep. By completing necessary calibration actions during these predetermined wake-up intervals, the device ensures the RC oscillator is recalibrated before the next long sleep period begins, preventing accumulated timing errors from degrading clock accuracy during extended power-saving states.
2Measurement precision
If the device wakes up frequently for calibration, then clock accuracy is maintained, but power consumption increases
Solution Approach 1:
The patent implements periodic wake-up events at predetermined intervals rather than continuous operation or irregular calibration. The device wakes up at regular, scheduled times to perform brief calibration operations on the RC oscillator, then returns to power management mode. This periodic approach balances timing accuracy maintenance with power conservation by calibrating only when necessary according to a fixed schedule.
Solution Approach 2:
The patent changes the operational parameters of the RC oscillator by switching between different power modes and calibration states. During normal operation, the oscillator runs at full power for accuracy. During power management mode, the device transitions to low-power states with reduced oscillator activity, waking up periodically to recalibrate. This parameter switching optimizes the trade-off between accuracy and power consumption based on operational requirements.
3Use of energy by moving object
If the RC oscillator runs at lowest power, then energy consumption is minimized, but timing precision degrades due to voltage and temperature changes
Solution Approach 1:
The patent incorporates feedback mechanisms where the device periodically measures the actual timing drift of the RC oscillator during power management mode and uses this information to adjust calibration parameters. By monitoring timing precision degradation and feeding this information back into the calibration process, the system can compensate for voltage and temperature effects on the low-power oscillator, maintaining acceptable timing accuracy while operating in energy-efficient mode.
Data Source
AI summary
Methods and wireless communication devices for sleep time management comprise determining a current remaining time before performing a scheduled activity, comparing the current remaining time with a predetermined sleep duration, setting a current sleep time according to a predefined setting and the current remaining time and updating the current remaining time according to the current sleep time in response to the current remaining time being greater than the predetermined sleep duration, or setting the current sleep time to the current remaining time and updating the current remaining time to zero in response to the current remaining time being less than or equal to the predetermined sleep duration. The methods and wireless communication devices further comprise entering a power management mode for a period of time equal to the current sleep time and exiting from the power management mode to perform a calibration operation after the current sleep time.