Fast Post-placement Rewiring Using Easily Detectable Functional Symmetries

Timing convergence problem arises when the estimations made during logic synthesis can not be met during physical design. In this paper, an efficient rewiring engine is proposed to explore maximal freedom after placement. The most important feature of this approach is that the existing placement solution is left intact throughout the optimization. A linear time algorithm is proposed to detect functional symmetries in the Boolean network and is used as the basis for rewiring. Integration with an existing gate sizing algorithm further proves the effectiveness of our technique. Experimental results are very promising

A compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast

A significant number of patients receiving breast-conserving surgery (BCS) for invasive carcinoma and ductal carcinoma in situ (DCIS) may need reoperation following tumor-positive margins from final histopathology tests. All current intraoperative margin assessment modalities have specific limitations. As a first step towards the development of a compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast, we prove that the system\u27s dimensions can be reduced without affecting imaging performance. We analysed the variation in noise and contrast to noise ratio (CNR) with decreasing system length using the edge illumination x-ray phase contrast imaging setup. Two-(planar) and three-(computed tomography (CT)) dimensional imaging acquisitions of custom phantoms and a breast tissue specimen were made. Dedicated phase retrieval algorithms were used to separate refraction and absorption signals. A \u27single-shot\u27 retrieval method was also used, to retrieve thickness map images, due to its simple acquisition procedure and reduced acquisition times. Experimental results were compared to numerical simulations where appropriate. The relative contribution of dark noise signal in integrating detectors is significant for low photon count statistics acquisitions. Under constant exposure factors and magnification, a more compact system provides an increase in CNR. Superior CNR results were obtained for refraction and thickness map images when compared to absorption images. Results indicate that the \u27single-shot\u27 acquisition method is preferable for a compact CT intraoperative specimen scanner; it allows for shorter acquisition times and its combination of the absorption and refraction signals ultimately leads to a higher contrast. The first CT images of a breast specimen acquired with the compact system provided promising results when compared to those of the longer length system

A compact system for intraoperative specimen imaging based on edge illumination x-ray phase contrast

“This is an author-created, un-copyedited version of an article accepted for publication/published in Physics in Medicine & Biology. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/1361-6560/ab4912

A methodology and algorithms for post-placement delay optimization

In this paper we present a placement-intelligent resynthesis methodology and optimization algorithms to meet post-layout timing constraints while at the same time reducing the interconnect congestion. We begin with the synthesized design netlist after initial placement and make incremental modi cations { taking placement into account { to generate a nal netlist and placement that meets the delay constraints after place and route. The algorithms described have been implemented aspart of a tool for placement based resynthesis. The tool has been used with a number of pre-optimized designs from industry and to obtain improvements in post-placement delays ranging from 13 to 22 % with improved routability. With today's submicron design processes the wiring parasitic becomes a dominant factor in the total delay of a timing path [1]. It is predicted that for a 0.5 micron process, the wiring can contribute as much as 60 % of the total delay. When the wiring e ect is dominant, traditional synthesis tools that use a fanout-based model may be optimizing a timing value which is signi cantly di erent from the actual post layout value. Another problem with traditional synthesis is in area estimation. Typically, the tools try to optimize the total gate area, and the interconnect area and the routability of the chip are not taken into account. As a result, although the total gate area of the synthesized netlist is quite small, it may not t into the assigned die area after layout.

An algebraic multigrid solver for analytical placement with layout based clustering

An efficient matrix solver is critical to the analytical placement. As the size of the matrix becomes huge, the multilevel methods turn out to be more efficient and more scalable. Algebraic Multigrid (AMG) is a multilevel technique to speedup the iterative matrix solver [10]. We apply the algebraic multigrid method to solve the linear equations that arise from the analytical placement. A layout based clustering scheme is put forward to generate coarsening levels for the multigrid method. The experimental results show that the algebraic multigrid solver is promising for analytical placement