Design of fast start-up high-Q oscillator for wireless sensor nodes transceiver frequency reference / Abdolraouf Rahmani

Abdolraouf , Rahmani (2025) Design of fast start-up high-Q oscillator for wireless sensor nodes transceiver frequency reference / Abdolraouf Rahmani. Masters thesis, Universiti Malaya.

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Abstract

With the prevalence of wireless sensor networks and the Internet of Things (IoT), optimizing power in battery-powered wireless nodes is crucial due to the inconvenience and cost of replacing batteries in remote areas. Synchronized power modulation between "Sleep" and "Active" states, known as burst mode activation, allows nodes to conserve power. However, frequent transitions between these states consume significant energy, highlighting the need to reduce the start-up time of the slowest component, the high-Q crystal oscillator. Additionally, to ensure improved synchronization within the network and a cost-effective IoT device manufacturing, the device should be produced with low start-up time variations and without the need for post-manufacture trimming respectively. This report introduces Zero-phase Lock Injection, a novel method based on resonance lock chirp injection to reliably reduce start-up time. It features Zero-phase Cross Detection, a low-power, variation-tolerant resonance frequency detection technique. Unlike previous detectors, this method does not require the variation-prone voltage reference and utilizes low power digital circuits. Additionally, Zero-phase adaptive chirp is proposed to advance resonance lock chirp injection by allowing for motional current phase correction which increases variation tolerance of start-up time while further reducing the start-up time. Both techniques have demonstrated start-up times that are robust against voltage, and temperature and even process variations. Post-layout simulations with Cadence Virtuoso on a 38.4 MHz crystal resonator with 1.0 V supply and 65-nm CMOS process confirms the feasibility of Zero-phase lock and Zero-phase adaptive chirp to effectively reduce and achieve start-up times of 175 μs and 170 μs respectively. This is achieved with state-of-art minimal temperature variations of 3% and 3.8% respectively. The results demonstrate the promising potential of Zero-phase Lock and Zero-phase Adaptive Chirp as viable variation-tolerant techniques, enabling enhanced synchronization without the need for costly post-manufacture trimming.

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