Browsing by Author "Sung, Wei-Hao"

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A Frequency Accuracy Enhanced Sub-10 mu W On-Chip Clock Generator for Energy Efficient Crystal-Less Wireless Biotelemetry Applications
(2010)
Sung, Wei-Hao
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Hsu, Shu-Yu
;
Yu, Jui-Yuan
;
Yu, Chien-Ying
;
Lee, Chen-Yi
A frequency accuracy enhanced clock generator is proposed for energy efficient crystal-less WBAN system. By applying a self-reference calibration and tracking a remote downlink wireless reference, the robust system clock with +/- 30ppm accuracy against both 20% voltage variation and 75 degrees C temperature variation is developed to enable over-Mbps uplink data transmission. Furthermore, the clock generator based on hysteresis delay cells consumes 7.6 mu W in 5MHz and is able to minimize significant always-on clock source power.
A Robust Frequency Tracking Loop for Energy-Efficient Crystalless WBAN Systems
(2011-10-01)
Sung, Wei-Hao
;
Yu, Jui-Yuan
;
Lee, Chen-Yi
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電機工程學系
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Department of Electrical and Computer Engineering
This brief presents a frequency tracking loop (FTL) to realize a crystalless wireless sensor node (WSN) for wireless body area network (WBAN). By tracking a remote wireless RF reference for system clock calibration, the proposed FTL allows WSNs to tolerate a large-frequency error from on-chip CMOS oscillators. Moreover, to achieve energy-efficient transmissions in crystalless, a sufficiently accurate convergence clock is required to enable burst overmegabits-per-second system throughput with minimized operation duty cycle. For the dedicated purpose, a comparison-based binary-search tracking scheme, which ensures accurate and robust convergence against noisy wireless channel, is further developed to manage the operation of FTL. The intermediate frequency back-end part of FTL is implemented in 90-nm CMOS process. Measurement results show that the FTL extends an initial tolerance of system clock error to +/- 3% and achieves a final quartz-crystal comparable +/- 50-ppm accuracy. This enables 4.85-Mb/s wireless links and improves 79% energy efficiency by RF operation-time reduction, giving a power-saved and miniaturized WSN device for WBAN applications.
An Energy-Efficient OFDM-Based Baseband Transceiver Design for Ubiquitous Healthcare Monitoring Applications
(2011)
Shih, Tzu-Chun
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Chen, Tsan-Wen
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Sung, Wei-Hao
;
Tsai, Ping-Yuan
;
Lee, Chen-Yi
This work proposes an orthogonal frequency division multiplexing (OFDM) based baseband transceiver design for wireless body area network (WBAN) application. Based on the analysis of the WBAN operation behavior, high transmission data rate and low power implementation techniques are proposed to reduce the transmission energy. An electrocardiography (ECG) transmission platform is also established with proposed design for system evaluation. This chip is implemented in a 90nm CMOS technology with the core size of 2.85 mm(2), and this baseband transceiver dissipates 357.14 uW with supply voltage 0.5 V. The proposed chip provides maximum 9.7 Mbps data rate, resulting in active duty cycle of 0.1763% and the transmission energy of 0.37 nJ / bit.