Leakage current is an important qualitative metric of LSI (Large Scale Integrated circuit). In this paper, we focus on reduction of leakage current variation under the process variation. Firstly, we derive a set of quadratic equations to evaluate delay and leakage current under the process variation. Using these equations, we discuss the cases of varying leakage current without degrading delay distribution and propose a procedure to reduce the leakage current variations. From the experiments, we show the proposed method effectively reduces the leakage current variation up to 50% at 90 percentile point of the distribution compared with the conventional design approach.

An autonatic layout scheme dedicated to bipolar analog modules is described. A layout model is settled in such a way that the VCC/GND line is laid out on top/bottom edge of a rectangular region, within which the whole elements are placed and interconnected. According to this simple modeling, a layout scheme can be constructed of a series of the following algorithms: First clustering is executed for partitioning a given circuit into clusters, each having connections with VCC and GND lines, and then linear ordering is applied to clusters so as to be placed in a one-dimensional array. After a relative placement of circuits elements in each cluster, a block compactor is implemented by means of packing blocks in each cluster into an idle space, and then a detailed router is conducted to attain 100% interconnection. Finally a layout compactor is invoked to pack all layout patterns into a rectangle of the minimum possible area. A number of implementation results are also shown to reveal the practicability of the proposed analog module generator.

In this paper, we present a new algorithm for statistical static timing analysis of a CMOS combinatorial circuit, which takes correlations into account to improve accuracy of the distribution of the maximum delay of the circuit. The correlations treated in the algorithm are not only the one between distributions of arrival times of input signals to a logic gate but also correlation between switching delays of a logic gate and correlation between interconnect delays of a net. We model each delay by a normal distribution, and use a normal distribution of two stochastic variables with a coefficient of correlation for computing the maximum of two delays. Since the algorithm takes the correlation into account, the time complexity is O(m2) in the worst-case, where m is the number of edges of the graph representing a given circuit. But, for real combinatorial circuits, the complexity is expected to be less than this.

This paper evaluates impact of self-heating in wire interconnection on signal propagation delay in an upcoming 32 nm process technology, using practical physical parameters. This paper examines a 64-bit data transmission model as one of the most heating cases. Experimental results show that the maximum wire temperature increase due to the self-heating appears in the case where the ratio of interconnect delay becomes largest compared to the driver delay. However, even in the most significant case which induces the maximum temperature rise of 11.0, the corresponding increase in the wire resistance is 1.99% and the resulting delay increase is only 1.15%, as for the assumed 32 nm process. A part of the impact reduction of wire self-heating on timing comes from the size-effect of nano-scale wires.

In this paper, we evaluate the effect of space-time coded cooperative relaying technique in multihop inter-vehicle communication (IVC) networks. The IVC systems have an issue that communication links are often blocked by obstacles such as heavy vehicles. The breakage of a radio link in multihop connections may significantly decrease the system throughput in multihop IVC networks. It is demonstrated through system-level evaluations that the cooperative relaying can offer remarkable capacity enhancement by exploiting multi-route diversity and overcoming accidental link breakage resulting from frequent topological changes.

This paper proposes a new flexible hardware model for pipelined design optimization. Using together with an RTL floorplanner, the flexible hardware model makes accurate and fine design space exploration possible. It is quite effective for deep submicron technology since estimation at high level has become a difficult problem and the design tuning at lower level of abstraction makes up the full design optimization task. The experimental results show that our approach reduces the slack time in the pipeline stages then achieves higher performance with a smaller area.