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.
Badush Dam, NW Iraq : A Geological Study
The river Tigris flows from Turkey towards Iraq in its northwestern part dissecting the whole Iraqi territory. During 1981– 1986 a very large earth fill dam was constructed, which is Mosul Dam impounding the flow of the Tigris River. It is the largest dam in Iraq and one of the largest in the Middle East. The geological conditions of the dam site and surroundings, however, are not suitable due to thick exposures of the Fatha Formation, which consists of marl, clay, limestone and gypsum. The gypsum and limestone beds are highly karstified causing severe problems to the dam foundation. Mosul dam suffers from serious problems due to the presence of karstified rocks; therefore, the Ministry of Irrigation in Baghdad, decided to construct a protection dam downstream of Mosul Dam; it is called Badush Dam. The geological conditions at Badush Dam site are the same as those at Mosul Dam site, which means the foundations of the dam are located on karstified rocks. Therefore, grouting works were planned and designed and it was partly performed from the beginning of the construction in 1988. The construction of the dam; however, stopped in 1991 due to the consequences of the First Gulf War. The constructed parts of the dam are (30 – 40) %. In this study, we have presented the main problems, which will cause real danger to Badush Dam, if its construction is re-started, and we have suggested many requirements to avoid any hazard that may cause the collapse of Badush Dam.