Amir Fathi

A low-power, fully programmable membership function generator using both transconductance and current modes

Abstract In this paper, a membership function generator (MFG) is presented which can produce triangular, trapezoidal, S-shaped or Z-shaped membership functions. The presented structure can operate in both trans-conductance (voltage–current) and current mode (current–current) with high programmability. The slope (keeping the height or width of the membership function constant), height (keeping the width constant) and width (keeping the height constant) of the membership function are independently programmable. Moreover, the width of the trapezoid can be varied without changing slope or height and all the generated shapes can be positioned horizontally. The topology, primarily, is presented in transconductance mode which can be converted to current mode with a little change in the input section of the circuit. Simulation results for the proposed circuit are presented in two operation modes. The most remarkable feature of the proposed MFG is its capability of generating outputs while consumes a very low amount of power. The analytical analysis of the proposed circuits is also given in HSPICE using TSMC 0.18 μm CMOS technology.

CMOS implementation of a fast 4-2 compressor for parallel accumulations

This paper discusses about the design of a novel and fast 4-2 compressor. To enhance the speed performance, some changes are performed in the truth table of conventional 4-2 compressor which leaded to reduction of gate level delay to 2 XOR logic gates plus 1 transistor for all parameters. Because of similar paths, there will be no need for extra buffers in low latency paths to equalize the delays. Therefore, the power dissipation will be decreased and the output waveforms will be free of any glitch. The delay of proposed architecture is 340ps which is simulated by HSPICE using TSMC 0.35µm CMOS technology.

High Speed Min/Max Architecture Based on a Novel Comparator in 0.18-μm CMOS Process

This paper describes the design of a high speed min/max architecture based on a new current comparator. The main advantage of the proposed circuit which employs a novel preamplifier-latch comparator is the higher operating frequency feature in comparison with previous works. Because the comparator can work in voltage mode, the min/max structure can be redesigned either in voltage or current mode. The designed comparator is refreshed without any external clock. Therefore, it does not degrade the speed performance of proposed min/max structure. These features along with low power consumption qualify the proposed architecture to be widely used in high speed fuzzy logic controllers (FLCs). Post-layout simulation results confirm 3.4 GS/s comparison rate with 9-bit resolution for a 0.9 V peak-to-peak input signal range for the comparator and 800 MHz operating frequency for min/max circuit. The power consumption of whole structure is 912 μW from a 1.8 V power supply using TSMC 0.18-μm CMOS technology.

Carrier velocity effect on carbon nanotube Schottky contact

One of the most important drawbacks which caused the silicon based technologies to their technical limitations is the instability of their products at nano-level. On the other side, carbon based materials such as carbon nanotube (CNT) as alternative materials have been involved in scientific efforts. Some of the important advantages of CNTs over silicon components are high mechanical strength, high sensing capability and large surface-to-volume ratio. In this article, the model of CNT Schottky transistor current which is under exterior applied voltage is employed. This model shows that its current has a weak dependence on thermal velocity corresponding to the small applied voltage. The conditions are quite different for high bias voltages which are independent of temperature. Our results indicate that the current is increased by Fermi velocity, but the I–V curves will not have considerable changes with the variations in number of carriers. It means that the current doesn’t increase sharply by voltage variations over different number of carriers.