Summary:
UCLA researchers in the Department of Electrical and Computer Engineering have developed a novel device to rapidly startup High-Q Oscillators which reduce power consumption of wearable electronic devices.
Background
Wearable digital devices and small wirelessly connected devices known as “Internet of Things” are used in a wide range of applications from healthcare monitors to vending machines. Many of these devices rely on the use of small batteries which limits their battery life. In order to expand their battery life and reduce maintenance, these devices use a technique known as duty cycling. This technique conserves power by quickly powering up and down circuits as needed, decreasing unnecessary power consumption. Duty cycle is primarily done by pre-energizing crystals or micro-electromechanical system (MEMS) with another “injection” oscillator at similar frequencies. When done properly, this can dramatically increase battery life. But due to variable environmental factors such as voltage, temperature, and fabrication errors generate mismatches between the frequencies of the injection oscillator and the crystal resulting in inefficient duty cycling. Attempts to address these mismatches such as using broad range injection oscillators or trimming the frequency error with factory calibrations, have failed to decrease startup time or only improve them under a restricting set of conditions limiting operational conditions that can be used. There is a need for an innovation that can address these mismatch errors and can expand the range of usable conditions.
Innovation
UCLA researchers have developed a device that rapidly calibrates injection oscillators upon startup. This allows fast startup of crystal oscillators in the range of microseconds without the performance loss. With this innovation, the frequency is able to match the resonant frequency to within sub-1000 ppm and can bypass mismatches associated with environmental and device variations. This drastically reduce the startup time resulting in an estimated decrease of 50% in the required startup energy. Furthermore, because of the calibration is included in the device, removes the need for factory calibration to be conducted reducing the need for frequent maintenance.
Patent: Fast startup of crystal and other high-Q oscillators
Potential Applications
- Reducing power consumption of digital devices
- Digital devices including Internet of Things
Advantages
- Lower power consumption of digital devices
- Digital devices that are more robust to environment and power fluctuations
- Requires less maintenance
State of Development
The device has been conceptualized, designed, and simulated. Prototypes of the device are being manufactured and tested
Related Materials:
H. Esmaeelzadeh and S. Pamarti, "A precisely-timed energy injection technique achieving 58/10/2μs start-up in 1.84/10/50MHz crystal oscillators," 2017 IEEE Custom Integrated Circuits Conference (CICC), Austin, TX, 2017, pp. 1-4, doi: 10.1109/CICC.2017.7993605.
J. B. Lechevallier, R. A. R. Van Der Zee and B. Nauta, "Fast & Energy Efficient Start-Up of Crystal Oscillators by Self-Timed Energy Injection," in IEEE Journal of Solid-State Circuits, vol. 54, no. 11, pp. 3107-3117, Nov. 2019, doi: 10.1109/JSSC.2019.2933143.