A low-power fast start-up crystal oscillator with an autonomous dynamically adjusted load

\u3cp\u3eAn energy-efficient fast start-up method for crystal oscillators is presented, which enables aggressive duty-cycled operation of IoT radios to minimize overall power consumption. A digitally controlled crystal oscillator using the proposed start-up technique in 90-nm CMOS is presented. Thanks to the dynamically adjusted load, the negative resistance is boosted, achieving a 13 × start-up time reduction and an overall power of 95μ W for a 24-MHz crystal oscillator at 1 V. A fully autonomous feedback loop detects the oscillators envelop and adjusts the load capacitance at start-up. Thanks to the low-power start-up circuits, both the start-up time and the start-up energy are reduced. In addition, the robustness and versatility of the proposed method is verified by measuring quartz crystals with different frequencies and quality factors, as well as measuring against temperature, supply voltage, and load capacitance variations.\u3c/p\u3

A low-power fast start-up crystal oscillator with an autonomous dynamically adjusted load

An energy-efficient fast start-up method for crystal oscillators is presented, which enables aggressive duty-cycled operation of IoT radios to minimize overall power consumption. A digitally controlled crystal oscillator using the proposed start-up technique in 90-nm CMOS is presented. Thanks to the dynamically adjusted load, the negative resistance is boosted, achieving a 13 × start-up time reduction and an overall power of 95μ W for a 24-MHz crystal oscillator at 1 V. A fully autonomous feedback loop detects the oscillators envelop and adjusts the load capacitance at start-up. Thanks to the low-power start-up circuits, both the start-up time and the start-up energy are reduced. In addition, the robustness and versatility of the proposed method is verified by measuring quartz crystals with different frequencies and quality factors, as well as measuring against temperature, supply voltage, and load capacitance variations

Low-Power Integrated Circuits For Biomedical Applications

With thousands new cases of spinal cord injury reported everyday, many people suffer from paralysis and loss of sensation in both legs. Beside the healthcare costs, such a state severely deteriorates the patients' quality of life and may even lead to additional medical conditions. Therefore, there is a growing need for cyber-physical systems to restore the walking ability through bypassing the damaged spinal cord. This goal can be achieved by monitoring and processing patient's brain signals to enable brain-directed control of prosthetic legs. Among several existing methods to record brain signals, electrocorticography (ECoG) has gained popularity due to being robust to motion artifacts, having high spatial resolution and signal to noise ratio, being moderately invasive and the possibility of chronic implantation of recording grids with no or minor scar tissue formation. The latest property is of particular importance for the whole system to be a viable fully implantable solution. Furthermore, the implanted system has to operate independently with no or minimal need of external hardware (e.g. a bulky personal computer) to be individually and socially accepted. To implement a fully implantable system, low-power and miniaturized electronics are needed to reduced heat generation, increase battery life-time and be minimally intrusive. These requirements indicate that many of the system's components should be custom-designed to integrated as much functionality as possible in a given real estate. This thesis presents silicon tested prototypes of several building blocks for the envisioned system, namely, ultra low-power brain signal acquisition front-ends, a low-power and inductorless MedRadio transceiver, and a fast start-up crystal oscillator. Brain signal acquisition front-ends provide low noise amplification of weak ECoG biosignals. MedRadio transceiver enables communication between the implant and end effectors or base station (e.g. prosthetic legs or desktop computer). Crystal oscillator generates the reference signal for other system's components such as analog to digital converter. Novel techniques to improve important performance parameters (power consumption, low noise operation and interference resilience) have been introduced. Electrical, in-vitro and in-vivo experimental measurements have verified the functionality and performance of each design