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Committee type：Academic society

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Committee type：Academic society

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Committee type：Academic society

researchmap

Committee type：Academic society

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Committee type：Academic society

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Grant amount：\3250000 （ Direct Cost: \2500000 、 Indirect Cost：\750000 ）

Effect of temperature variation on integrated circuits for analog signal processing in sensor network was considered and schemes for maintaining circuit performance were proposed. First, MOSFET model is improved for the weak inversion region to express dependency on substrate potential and temperature. Second, a 0.6-V wide-dynamic range filter, which had been designed and implemented by a group of this researcher, was analyzed based on the model described above and its sensitivity with respect to temperature was suppressed by use of a bias voltage source with a negative temperature coefficient. Last, current mirrors are investigated and less than 1-% error between input and output currents at 400 K was achieved through analysis based on the model and formulation for the optimum design.

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Grant amount：\3120000 （ Direct Cost: \2400000 、 Indirect Cost：\720000 ）

An integrated circuit for low-frequency signal processing is developed to measure biological signals through wireless communication with portable equipments which are powered by energy source, the supply voltage of which is less than 1 V. First, filters for noise suppression, band limitation and baseband modulation are designed aiming at the point that the low-voltage and low-power filter structure which we have proposed is appropriate for baseband signal processing. A practical 0.6-V filter processing sensor signals is obtained even with 0.18-μm technology to achieve 89-dB dynamic range. Second, analog-to-digital converters (ADCs) following band limitation filters are considered. Successive approximation (SA),ΔΣ, and signal decomposition based pipeline types of architectures are investigated for low frequency and low voltage. Their noise performances are theoretically analyzed in detail and some techniques to enlarge signal-to-noise ratio by changing both wasteful structure are proposed. Last, digital substrate noise is coped with. Effectiveness with respect to a lot of noise sources are taken into account and a reliable simple model is introduced so that noise propagation in 3-D bulk is quantitatively discussed and 2 topologies effective for substrate noise suppression are derived. In conclusion, we are now sure that the aimed baseband signal processing is realizable with less than 0.8V.

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Grant amount：\1500000 （ Direct Cost: \1500000 ）

これまでに実現した低電圧回路を利用して,低電力フィルタを実現した.ます,二つの低電圧回路が電源電圧を分割して使用し,消費する電流が共通となるように,電源間に直列に接続(縦積み)にした構成を提案した.使用可能な電源電圧に余裕がある場合に発生する余分な電力損失を減らすことができる.単に接続しただけでは上下段の回路の信号電流が異なるため動作点がずれてしまうことから,上下二つ回路の接続点を定電位回路で固定する.次に,この構成法の具体的な適用例として,既に動作を確認している0.6V積分器を利用して,2次低域通過フィルタを設計し,試作と測定を通して性能を評価した.電源電圧1.2Vの下で,音声帯域信号処理への応用が可能な2kHz帯域のフィルタが動作し,理想特性と非常によく一致する周波数特性を得られている.消費電力は18μWと超低消費電力であり,また,60dB以上のダイナミックレンジを達成できている.縦積み構成は上下段間の節点に定電位回路を要するため,その消費電力が余計に必要になる懸念があったが,この設計例では全体のおおよそ1割に止められている.さらに本研究では,上下段の回路の特性にトランジスタの基板効果に起因する僅かな不整合が生じる問題も考察し,改善手法を検討した.以上の結栗は,基底アナログ信号の処理回路を低電力化するのに縦積み構成が有効であることを示しており,乾電池等により駆動しても長時間使用が可能な携帯電子機器の設計に寄与しうる成果である.

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Grant amount：\6900000 （ Direct Cost: \6900000 ）

Demands on high performance mixed-signal integrated circuits are increasing because of the advancing of multimedia technologies. Periodical behavior of digital circuits produces what so called digital substrate noise. This noise will deteriorate analog circuit performance and is a big problem to be solved.
A passive guard ring has been commonly used to reduce the substrate fluctuation. However, it only suppresses the noise coupled through a substrate surface and has quite small effect on noise transfered through the deep portion of a substrate. This project proposes an active shield circuit to solve digital substrate noise problem. The proposed active shield circuit will generate an inverting signal to the digital noise and cancel out it. To improve cancellation performance layout of the active shield circuit, analog circuits and digital circuits is considered, and an automatic control technique is proposed. The validity of the proposed techniques is confirmed through experiments and simulations.

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Grant amount：\14500000 （ Direct Cost: \14500000 ）

The aim of this project is to build up a design system for analog circuits in mixed-signal LSIs, which are expected to play an important role in 21st century. The following results are obtained in the project.
(1) In order to build such a system analog basic building blocks under low-power supply voltages are proposed. The circuits are applied to a synthesis of a △ΣAS Analog-to-Digital converter as an example.
(2) Switched-capacitor circuits are discrete-time signal processing ones and also important analog building blocks Since sitched-capacitor circuits have a clock feedthrough problem, a method to reduce the clock feedthrough effect is proposed.
(3) To help analog circuit designs instead of a small number of analog circuit designers automatic analog circuit design algorithm is proposed.
(4) To reduce noise from digital circuits via a substrate active gurad band circuit is proposed.
Investigation for excellent analog circuit layouts and combination of all results obtained above are left as future problems.

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