Identyfikacja parametrów dynamicznych linii szybkich przeniesień oraz globalnych linii zegarowych w układach programowalnych Spartan-6

W artykule przedstawiono analizę parametrów dynamicznych linii szybkich przeniesień arytmetycznych oraz globalnych linii zegarowych w układzie FPGA Spartan-6 firmy Xilinx. Określono opóźnienia sygnału zegarowego oraz impulsu propagującego się w liniach szybkich przeniesień w oparciu o model czasowy układu. Wyniki symulacji zweryfikowano eksperymentalnie. Ponadto, w artykule określono wpływ warunków otoczenia (temperatury i napięcia zasilania) na opóźnienia w układzie.

This paper presents the analysis of dynamic parameters of fast carry chains and global clock network in Spartan-6 (Xilinx) FPGA devices. The clock signal distribution and the carry chain structure are described in Section 2 (Fig. 1) and in Section 3 (Fig. 3) [1], respectively. Based on the Spartan 6 timing model [2], propagation delays in 32 time coding lines were examined. A relatively large clock skew was observed on the border of some clock regions (Fig. 2). The look ahead carry propagation was also identified. This helped to improve the resolution of coding lines [3] by eliminating death bins. Thanks to the timing model, two different types of coding lines were identified in two kind of SLICEs (Section 3, SLICEL in Fig. 4a and SLICEM in Fig. 4b). The simulation results were compared with the experimental ones obtained from the statistical code density test [4]. The 3-dimensional maps of bin widths (delays) were created to show actual differences between each of 32 coding lines (Fig. 5). The influence of temperature (Fig. 6) and power supply (Fig. 7) on delays in FPGA were also tested based on the behavior of the time coding lines resolution (Section 4). The similar clock network distribution and carry chain structures are also used in the newest FPGAs from Xilinx (Artix, Kintex, Virtex-7). The presented results can be applied to a broad class of programmable devices.