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Comparative analysis of the memory elements and sense amplifiers for high-temperature VLSI RAM  

 Kiseleva A.A.
 Krasnyuk A.A.
 Trepalin A.P.
Date of publication

 The fundamental scientific problem is the determination of physical and technological and structural-circuit solutions and design techniques to ensure the functional operability of the integral elements of large scale integrated memory circuits at extremely high levels of temperature and external destructive factors. Memory elements and sense amplifiers (SA) are one of the most critical circuits in CMOS VLSI RAM.
Investigation of the influence of temperature effects and comparative analysis performed by the simulation 6-transistor SRAM cells and individual transistors "P" and "N" - type, as well as two variants sense amplifiers with using models of SOI CMOS several high-temperature technological processes - native SOI CMOS 0.5 m and industrial High Temperature High Voltage SOI XI10 from X-FAB Semiconductor Foundries AG ( Germany).
A comparative analysis was conducted on the following key features: I-V characteristics of transistors at temperatures from -60C to 300C; the temperature dependence of the switching characteristics of the flip-flop memory cells; SNM (static noise margins); the dependence of the setting time the logical zero and the unit from temperature. The simulation was performed using the software Virtuoso (R) Design Analog Environment CAD Cadence. The simulation results clearly showed the formation of ZTC points (zero-temperature coefficient) for the models available on the I-V characteristics of HTE transistors. Given that the results showed the dependence of the formation of ZTC points in the linear area and the saturation area of I-V characteristics of the transistor structures, as well as the actual uncertainty due to the influence of leakage currents, concludes that the applicability of this method of thermal stabilization, primarily for analog circuit elements. CMOS inverters for all investigated models showed complete functionality and very small changes in static characteristics at temperatures up to 300 C. This allows to make a conclusion about significant decrease in the noise immunity of the memory cells on the basis of trigger elements.. Readout time with increasing temperature from 25C to 300C predictable increases almost 2 times that fully corresponds to a proportional decrease in the carrier mobility of the channel.
The sense amplifiers are one of the most critical circuits in the periphery of CMOS memories. Simulation results of speed ratios and temperature dependencies of the sense amplifier actually corresponds to the memory cells. The relative decrease in the critical charge in the selected temperature range of 40% is consistent with the critical charge, depending on the temperature of the reference memory cells. However, analysis of these dependences suggests that HTE 1,0 m technology significantly less sensitive to variations of temperatures.
 sense amplifier, SRAM, simulate, high temperature electronics, topology of IC.
Library reference
 Kiseleva A.A., Krasnyuk A.A., Trepalin A.P. Comparative analysis of the memory elements and sense amplifiers for high-temperature VLSI RAM // Problems of Perspective Micro- and Nanoelectronic Systems Development - 2016. Proceedings / edited by A. Stempkovsky, Moscow, IPPM RAS, 2016. Part 3. P. 87-92.
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