Ultralow-power Circuit Techniques for Applications with Microscale Energy
あらゆるモノにセンサを取り付けインターネットに 接続することにより新たな価値を創出する IoT (Internet of things)社会の実現に向けて,様々な技術レ イヤーの研究開発が盛んに行われている.IoT技術の 今後の問題の一つに,モノをインターネットに接続す るための近距離無線センサ端末の電源問題がある.電 池駆動のセンサ端末は電池交換が必要となるからで ある.端末の電源問題を解決する一つの手法として, 我々の身の回りに微小ながら常に存在する熱,光,振 動といったアンビエントエネルギー源を活用するマイ クロ環境発電技術が注目されている [1]. 発電電力がミリワット級の環境発電応用としては, 照明用スイッチに電磁誘導型の発電素子を組込み,無 線で照明の ON/OFF制御を行う無線スイッチ [2]や, 列車の車軸に振動発電素子を組込み,無線で車軸のベ アリングを監視するモニタリングシステム [3] が,既 に実用化されている.我々は,人間の尿で発電する尿
A Sub-0.5 V Differential ED-CMOS/SOI Circuit with Over-1-GHz Operation
This paper describes a speed-oriented ullralow-voltage and low-power SOI circuit technique based on a differential enhancementand depletion-mode (ED)-MOS circuit. Combining an ED-MOS circuit block for critical paths and a multi-V th CMOS circuit block for noncritical path, that is, the so-called differential ED-CMOS/SOI circuit, makes it possible to achieve low-power and ultrahigh-speed operation of over 1 GHz at a supply voltage of less than 0.5 V. As two applications of the differential ED-CMOS/SOI circuit, a multi-stage frequency divider that uses the ED-MOS circuit in a first-stage frequency divider and a pipelined adder with a CMOS pipeline register are described in detail. To verify the effectiveness of the ED-CMOS/SOI circuit scheme, we fabricated a 1/8 frequency divider and a 32-bit binary look-ahead carry (BLC) adder using the 0.25-μm MTCMOS/SOI process. The frequency divider operates down to 0.3 V with a maximum operating frequency of 3.6GHz while suppressing power dissipation to 0.3 mW. The 32-bit adder operates at a frequency of I GHz at 0.5 V.
The etiology and surgical management of tracheal collapse in calves.
The mean ages of 10 calves with tracheal collapse were 2.7 weeks at onset of clinical signs and 9.4 weeks at presentation for treatment. Inspiratory and expiratory dyspnea and stunted growth were the most common clinical signs. There were abnormalities of the cranial ribs consistent with healing fractures with redundant callus in eight lateral thoracic radiographs. Tracheal collapse in calves may result from cranial thoracic trauma during or soon after birth. Short polypropylene ring prostheses made from 60 ml syringe barrels were placed on the tracheas of four calves with cervical tracheal collapse. There were cranial rib masses in all calves and resection of the right first and second ribs was necessary in one calf to allow placement of prostheses. Dyspnea was relieved in all calves. One calf died of unrelated causes in year 3, and one calf had recurrence of clinical signs at month 5 and was euthanatized. In both calves, tracheal stenosis resulted from continued growth and infolding of the trachea within the constraints of the prostheses. One calf was alive at month 11, and one calf died of acute bronchopneumonia on day 2. Removal of tracheal prostheses in calves is recommended after 2 to 3 months if clinical signs recur.