Current Issue : July - September Volume : 2011 Issue Number : 3 Articles : 3 Articles
IP cores are widely used in modern SOC designs. Hierarchical design has been employed for the growing design complexity, which stimulates the need for fixed-outline floorplanning. Meanwhile, buffer insertion is usually adopted to meet the timing requirement. In this paper, buffer insertion is considered with a fixed-outline constraint using Less Flexibility First (LFF) algorithm. Compared with Simulated Annealing (SA), our work is able to distinguish geometric differences between two floorplan candidates, even if they have the same topological structure. This is helpful to get a better result for buffer planning since buffer insertion is quite sensitive to a geometric change. We also extend the previous LFF to a more robust version called Sliced-LFF to improve buffer planning. Moreover, a 2-staged LFF framework and a post-greedy procedure are introduced based on our net-classing strategy and finally achieve a significant improvement on the success rate of buffer insertion (40.7% and 37.1% in different feature sizes). Moreover, our work is much faster than SA, since it is deterministic without iterations....
In the advent of smaller devices, a significant increase in the density of on-chip components has raised congestion and overflow as critical issues in VLSI physical design automation. In this paper, we present novel techniques for reducing congestion and minimizing overflows. Our methods are based on ripping up nets that go through the congested areas and replacing them with congestion-aware topologies. Our contributions can be summarized as follows. First, we present several efficient algorithms for finding congestion-aware Steiner trees that is, trees that avoid congested areas of the chip. Next, we show that the novel technique of network coding can lead to further improvements in routability, reduction of congestion, and overflow avoidance. Finally, we present an algorithm for identifying efficient congestion-aware network coding topologies. We evaluate the performance of the proposed algorithms through extensive simulations....
Using a specific input-restructuring sequence, a new VLSI algorithm and architecture have been derived for a high throughput memory-based systolic array VLSI implementation of a discrete cosine transform. The proposed restructuring technique transforms the DCT algorithm into a cycle-convolution and a pseudo-cycle convolution structure as basic computational forms. The proposed solution has been specially designed to have good fixed-point error performances that have been exploited to further reduce the hardware complexity and power consumption. It leads to a ROM based VLSI kernel with good quantization properties. A parallel VLSI algorithm and architecture with a good fixed point implementation appropriate for a memory-based implementation have been obtained. The proposed algorithm can be mapped onto two linear systolic arrays with similar length and form. They can be further efficiently merged into a single array using an appropriate hardware sharing technique. A highly efficient VLSI chip can be thus obtained with appealing features as good architectural topology, processing speed, hardware complexity and I/O costs. Moreover, the proposed solution substantially reduces the hardware overhead involved by the pre-processing stage that for short length DCT consumes an important percentage of the chip area...
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