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Journal of Information Science and Engineering, Vol. 24 No. 1, pp. 115-127 (January 2008)

An Effective Decap Insertion Method Considering Power Supply Noise during Floorplanning*

Chao-Hung Lu, Hung-Ming Chen** and Chien-Nan Jimmy Liu
Department of Electrical Engineering
National Central University
Taoyuan, 320 Taiwan
E-mail: {chlu; jimmy}@ee.ncu.edu.tw
**Department of Electronics Engineering and SoC Research Center
National Chiao Tung University
Hsinchu, 300 Taiwan
E-mail: hmchen@mail.nctu.edu.tw

As VLSI technology enters the nanometer era, the supply voltage is continually dropped. This condition helps to reduce the power dissipation, but make the power integrity problem become worse. Employing decoupling capacitances (decap) at floorplan stage has been a common approach to alleviate the supply noise problem. However, the decap budget is often overly estimated in previous researches. Besides the decap budget computation, the available floorplan space does not fully used in previous works. In one floorplan, it usually has many available spaces except the empty space that could be used to insert the decap without increasing the floorplan area. Therefore, our goal in this work is to develop a better model to calculate the required decap to solve the power supply noise problem of area-array based designs and to increase he usage of the available space in the floorplan to reduce the area overhead caused by decap insertion. The experimental results are encouraging. Compared with other approaches, our algorithm can reduce 52.6% decap budget on the MCNC benchmarks but still keep the power supply noise in the given constraint. The final floorplan areas with decap are also less than the numbers reported in previous papers.

Keywords: decoupling capacitance, floorplanning, physical design, power estimation, area-array architecture

Full Text () Retrieve PDF document (200801_08.pdf)

Received February 2, 2007; accepted July 13, 2007.
Communicated by K. Robert Lai, Yu-Chee Tseng and Shu-Yuan Chen.
*This work was supported in part by the National Science Council of Taiwan, R.O.C. under contract NSC 96-2220-E-009-016 and NSC 96-2221-E-008-120.