Slave Module Clock Signal Generation for Duty-Cycled Wireless
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Solution Overview
Problem
Existing wireless radios for implantable and disposable applications are bulky and costly due to the need for crystal-based oscillators, which are expensive and increase the size and cost of the radio, and current crystal-less solutions result in high power consumption and short battery life without a wakeup timer.
Innovation Solution
A system comprising a master and slave module where the slave module generates a clock signal with a period equal to the time interval of data packets transmitted by the master module, allowing for sleep/wakeup control without a crystal-based oscillator, using an on-chip CMOS oscillator for precise timing and reducing the overall size and cost of the radio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If crystal-based oscillators are used for wakeup timer, then timing precision is improved, but size and cost increase
Solution Approach 1:
The patent uses a copy of the master node's timing signal by generating a local clock signal that replicates the packet transmission pattern. The slave node captures the rising and falling edges of received packets and uses these to generate a local clock signal that copies the master's timing, eliminating the need for a separate crystal oscillator while maintaining synchronization precision.
Solution Approach 2:
The received packet signal serves multiple functions: it provides both the data communication and the timing reference for the wakeup timer. The same signal that carries information also defines the clock edges, making the system multi-functional and eliminating the need for dedicated timing components.
2Measurement precision
If crystal-based oscillators are used for wakeup timer, then timing precision is improved, but cost increases
Solution Approach 1:
The patent uses a copy of the master node's timing signal by generating a local clock signal that replicates the packet transmission pattern. The slave node captures the rising and falling edges of received packets and uses these to generate a local clock signal that copies the master's timing, eliminating the need for a separate crystal oscillator while maintaining synchronization precision.
Solution Approach 2:
The patent extracts the timing information directly from the received packet signal, separating the timing function from the data communication function. By taking out only the essential timing edges from the packet signal, the system eliminates the need for expensive crystal oscillators while preserving timing precision.
3Area of stationary object
If RC oscillator is used without wakeup timer, then size is reduced, but power consumption increases
Solution Approach 1:
The patent implements periodic sleep/wakeup cycles by using the local clock signal to trigger the wakeup timer at regular intervals corresponding to the master's packet transmission period. The slave node sleeps during intervals and wakes up periodically to check for packets, enabling duty-cycled operation that reduces power consumption while maintaining small size.
Solution Approach 2:
The patent performs preliminary synchronization by capturing packet edges and generating the local clock signal before duty-cycled operation begins. This preliminary action establishes the timing reference needed for subsequent periodic sleep/wakeup cycles, enabling low-power operation without requiring a crystal oscillator.
4Area of stationary object
If RC oscillator is used without wakeup timer, then size is reduced, but battery lifetime decreases
Solution Approach 1:
The patent implements periodic sleep/wakeup cycles by using the local clock signal to trigger the wakeup timer at regular intervals corresponding to the master's packet transmission period. The slave node sleeps during intervals and wakes up periodically to check for packets, enabling duty-cycled operation that reduces power consumption while maintaining small size.
Solution Approach 2:
The patent enables the slave node to self-synchronize with the master node by automatically capturing packet edges and generating its own clock signal. This self-service capability eliminates the need for external calibration or continuous active operation, extending battery lifetime while maintaining small size through duty-cycled operation.
Data Source
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Figure 3A~3B
AI summary
A system (10) is provided for generating time reference in duty-cycled wireless communications. The system (10) comprises at least one master module (11) comprising a master transceiver (13) adapted to transmit data packets. The system (10) further comprises at least one slave module (12) comprising a slave transceiver (14) adapted to receive the data packets. The slave module (12) further comprises a signal generating means (16) adapted to generate a clock signal with a period equal to the time interval of two data packets transmitted by the master module (11). Moreover, the slave module (12) further comprises a slave timer (18) adapted to utilize the clock signal as a time reference in order to perform the sleep/wakeup control for the slave module (12).