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YoungKyu JANG Ik-Joon CHANG Jinsang KIM
PD-SOI (Partial Depleted Silicon On Insulator) process is a good candidate technology for space system designs, since it features excellent insulation to the silicon substrate compared to the conventional bulk CMOS process. However, the radioactive particles from the low earth orbit can causes single event transient (SET) or abrupt charge collection in a circuit node, leading to a logical error in space systems. Also, the side effects such as the history effect and the kink effect in PD-SOI technology cause the threshold voltage variation, degrading the circuit performance. We propose SET-tolerant PD-SOI CMOS logic circuits using a novel active body-bias scheme. Simulation results show that the proposed circuits are more effective to SET and the side effects as well.
Masaaki IIJIMA Kayoko SETO Masahiro NUMA Akira TADA Takashi IPPOSHI
Instability of SRAM memory cells derived from aggressive technology scaling has been recently one of the most significant issues. Although a 7T-SRAM cell with an area-tolerable separated read port improves read margins even at sub-1V, it unfortunately results in degradation of write margins. In order to assist the write operation, we address a new memory cell employing a look-ahead body-bias which dynamically controls the threshold voltage. Simulation results have shown improvement in both the write margins and access time without increasing the leakage power derived from the body-bias.
Masaaki IIJIMA Masayuki KITAMURA Masahiro NUMA Akira TADA Takashi IPPOSHI Shigeto MAEGAWA
In this paper, we propose an Active Body-biasing Controlled (ABC)-Bootstrap PTL (Pass-Transistor Logic) on PD-SOI for ultra low power design. Although simply lowering the supply voltage (VDD) causes a lack of driving power, our boosted voltage scheme employing a strong capacitive coupling with ABC-SOI improves a driving power and allows lower voltage operation. We also present an SOI-SRAM design boosting the word line (WL) voltage higher than VDD in short transition time without dual power supply rails. Simulation results have shown improvement in both the delay time and power consumption.
Kazuki FUKUOKA Masaaki IIJIMA Kenji HAMADA Masahiro NUMA Akira TADA
This paper presents a novel layout approach using dual supply voltage technique. In Placing and Routing (P&R) phase, conventional approaches for dual supply voltages need to separate low supply voltage cells from high voltage ones. Consequently its layout tends to be complex compared with single supply voltage layout. Our layout approach uses cells having two supply voltage rails. Making these cells is difficult in bulk due to increase in area by n-well isolation or in delay by negative body bias caused by sharing n-well. On the other hand, making cells with two supply voltage rails is easy in body-tied PD-SOI owing to trench isolation of each body of transistor. Since our approach for dual supply voltages offers freedom for placement as much as conventional ones for single supply voltage, exsting P&R tools can be used without special operation. Simulation results with MCNC circuits and adders show that our approach reduces power by 23% and 25%, respectively, showing almost the same delay with single supply voltage layout.