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成果報告書詳細
管理番号20180000000181
タイトル*平成29年度中間年報 IoT 推進のための横断技術開発プロジェクト 超低消費電力データ収集システムの研究開発6(国立大学法人東京工業大学)
公開日2018/6/2
報告書年度2017 - 2017
委託先名国立大学法人東京工業大学
プロジェクト番号P16007
部署名IoT推進部
和文要約
英文要約Title: Project to Develop Cross-Sectoral Technologies for IoT Promotion / Development of Ultra Low Power Data Collection Systems (FY2016-FY2018) FY2017 Annual Report

In this work, a Ultra-Low-Power (ULP) transceiver is studied to realize a battery-less energy-harvesting wireless sensor node for IoT. The present ULP wireless transceiver still requires a power consumption of more than 10mW.
Even in a duty-cycling operation, a sub-mW order of power consumption is still required. The conventional energy-harvesting technologies such as solar need special unstable environment even if it has a capability of more than 1mW in a small IoT node. This will seriously limit potential application of wireless sensor node. Further power saving techniques are required to enhance wider IoT device deployment.
In this research project, (1) normally-off wireless transceiver, (2) normally-off scalable analog-to-digital converter (ADC), and (3) ULP crystal oscillator are investigated. Typical analog circuits such as amplifier and oscillator needs static bias current while digital circuits need only switching current. This is one of the most significant features in analog circuits that causes larger power consumption. In this work, a normally-off analog circuit technique is proposed to reduce the power consumption, and a sub-uW operation can be realized in a duty-cycling operation. This year, a synthesizable PLL achieving 1-clock synchronization has been developed.
The receiver is also designed, and the power consumption is 3.3mW.
The transmitter achieves 40% efficiency for 0dBm output.
ADC is one more important key building block in IoT sensor nodes. To cover various application range, ADC has to operate with 6-14bit resolution at up to 10MHz conversion speed with scalable power consumption. To realize this characteristics, a new-type ADC is investigated to realize the above required operation for IoT sensor nodes. This year, a noise shaping SAR ADC with performance scalability by changing an over sampling ratio has been developed. Measurement results show that the proposed ADC has resolution range of 6-14bit and power consumption of less than 1uW at 1kS/s operation.
A crystal oscillator is a very common but power hungry building block in a duty-cycling operation. The crystal oscillator has to keep working even under the duty-cycle operation for real time clock (RTC), and tens of MHz clock frequency is also required for microprocessor and wireless transceiver. In this case, a fast wake-up is a key requirement to reduce the total energy. This year, a fast wake-up crystal oscillator has been developed, using a gm-boosting technique. At 40MHz oscillation, the proposed crystal oscillator demonstrates a start-up energy and time of 37.2nJ and 64us, respectively. Moreover, an RTC using C-class amplifier for reducing the power consumption has been developed. The proposed RTC consumes only less than 100nW.
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