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Hiroki NAKAHARA Tsutomu SASAO Munehiro MATSUURA
A Decision Diagram Machine (DDM) is a special-purpose processor that has special instructions to evaluate a decision diagram. Since the DDM uses only a limited number of instructions, it is faster than the general-purpose Micro Processor Unit (MPU). Also, the architecture for the DDM is much simpler than that for an MPU. This paper presents a packet classifier using a parallel EVMDD (k) machine. To reduce computation time and code size, first, a set of rules for a packet classifier is partitioned into groups. Then, the parallel EVMDD (k) machine evaluates them. To further speed-up for the standard EVMDD (k) machine, we propose the prefetching EVMDD (k) machine which reads both the index and the jump address at the same time. The prefetching EVMDD (k) machine is 2.4 times faster than the standard one using the same memory size. We implemented a parallel prefetching EVMDD (k) machine consisting of 30 machines on an FPGA, and compared it with the Intel's Core i5 microprocessor running at 1.7GHz. Our parallel machine is 15.1-77.5 times faster than the Core i5, and it requires only 8.1-58.5 percents of the memory for the Core i5.
This paper describes an 11-Gb/s CMOS demultiplexer (DEMUX) using redundant multi-valued logic (RMVL). The proposed circuit is received to serial binary data and is converted to parallel redundant multi-valued data. The converted data are reconverted to parallel binary data. By the redundant multi-valued data conversion, the RMVL makes it possible to achieve higher operating speeds than that of a conventional binary logic. The implemented DEMUX consists of eight integrators. The DEMUX is designed with 0.35 µm standard CMOS process. The validity and effectiveness are verified through HSPICE simulation. The DEMUX is achieved to the maximum data rate of 11-Gb/s and the average power consumption of 69.43 mW. This circuit is expected to operate at higher speed than 11-Gb/s in the deep-submicron process of the high operating frequency.
Jing SHEN Koichi TANNO Okihiko ISHIZUKA Zheng TANG
A neuron-MOS transistor (νMOS) is applied to current-mode multi-valued logic (MVL) circuits. First, a novel low-voltage and low-power νMOS current mirror is presented. Then, a threshold detector and a quaternary T-gate using the proposed νMOS current mirrors are proposed. The minimum output voltage of the νMOS current mirror is decreased by VT (threshold voltage), compared with the conventional double cascode current mirror. The νMOS threshold detector is built on a νMOS current comparator originally composed of νMOS current mirrors. It has a high output swing and sharp transfer characteristics. The gradient of the proposed comparator output in the transfer region can be increased 6.3-fold compared with that in the conventional comparator. Along with improved operation of the novel current comparator, the discriminative ability of the proposed νMOS threshold detector is also increased. The performances of the proposed circuits are validated by HSPICE with Motorola 1.5 µm CMOS device parameters. Furthermore, the operation of a νMOS current mirror is also confirmed through experiments on test chips fabricated by VDEC*. The active area of the proposed νMOS current mirror is 63 µm 51 µm.
Grant POGOSYAN Takashi NAKAMURA
In practical logic design circuits are built by composing certain types of gates. Each gate itself is a simple circuits with one, two or three inputs and one output, which implements an elementary logic function. These functions are called the generators. For the general purpose the set of generators is considered to be functionally complete, i. e. , it is able to express any logic function under chosen rules compositions. A basis is a functionally complete set of logic functions that contains no complete proper subset. Providing compactness and expressibility of the generators the notion of a basis, however, ignores the optimality of implementations. Efficiently irreducible generating set, termed ε-basis, is an irreducible set of generators which guarantees an optimal implementation of every function, with respect to the number of literals in its formal expression. The notion of ε-basis is significant in the composition of functions, since the classical definition of basis does not consider the efficiency of implementation. In case of Boolean functions, for two-input (dyadic) generators it has been shown that an ε-basis consists of all monadic functions, constants, and only two dyadic functions from certain classes. In this paper, expanding the domain of basic operations from dyadic to triadic, we study the efficiency of sets of 3-input gates as generators. This expansion decreases the complexity of functions (hence, the complexity of functional circuits to be designed). Gaining an evident merit in the complexity, we have to pay a price by a considerable increase of the number of such generators for the multiple valued circuits. However, in the case of Boolean operations this number is still very small, and it will certainly be useful to consider this approach in the practical circuit design. This paper provides a criterion for a generating set of triadic operations of k-valued logic to be efficiently irreducible. In the case of Boolean functions it is shown that there exist exactly five types of classes of triadic operations which constitute an ε-basis. A typical example of generator set which forms a triadic ε-basis, is also shown.