Praca poświęcona jest problematyce syntezy komparatorów binarnych w strukturach CPLD/FPGA. Opracowano metody opisu komparatorów w postaci piramidalnych struktur hierarchicznych. Do budowy komparatorów wykorzystano język Verilog i edytor graficzny. Badania eksperymentalne wykonano dla komparatorów 64-bitowych w środowisku Quartus II firmy Altera. Przeprowadzone badania wykazały, że istnieją struktury hierarchiczne, które są bardziej efektywne od wbudowanej funkcji lpm_compare pakietu Quartus II. W najlepszym przypadku uzyskano zmniejszenie maksymalnego czasu propagacji o 44%.
EN
The paper deals with the problem of binary comparator synthesis in CPLD/FPGA structures. Comparators were built with the usage of the Verilog language and the Quartus II graphics editor [10]. Section 1 describes the notion of a digital comparator, its basic usage [1-4] and research directions [6-10]. Section 2 presents the general hierarchical structure of the comparator (Fig. 2). Section 3 describes the method of building new hierarchical structures of 64-bit comparators. Section 4 presents the results of experimental research. Comparators were built and tested in the Altera Quartus II environment. In the experimental research, the 64-bit hierarchical comparators were compared with the 64-bit comparator built with the direct usage of the lpm_compare library function of the Quartus II package. The research was conducted on three CPLD families (MAX 3000 A, MAX II and MAX V) and two FPGA families (Cyclone III and Arria II GX). Three parameters were compared: implementation cost, maximum propagation delay and overall power dissipation. The conducted research demonstrates the existence of hierarchical structures which are better than the in-built lpm_compare function. For the MAX 3000 A family, the implemented hierarchical methods of comparator synthesis show the improved results: 32% in the implementation cost, 44% in the maximum propagation delay and 18% in the overall power dissipation. The improved results for Arria II are as follows: 17% in the implementation cost and 26% in the maximum propagation delay.
Praca dotyczy syntezy komparatorów binarnych w strukturach CPLD/FPGA. Do budowy komparatorów wykorzystano struktury hierarchiczne i równoległo-szeregowe metody syntezy. Badania eksperymentalne wykonano dla komparatorów 128-bitowych oraz 256-bitowych w środowisku Quartus II firmy Altera. Wybrane parametry porównano z wynikami uzyskanymi za pomocą funkcji lpm_compare. Dla komparatorów 128-bitowych uzyskano zmniejszenie kosztu realizacji o 13% oraz zmniejszenie ich maksymalnego czasu propagacji do 38%. W przypadku komparatorów 256-bitowych uzyskano zmniejszenie kosztu realizacji o 19% oraz zmniejszenie ich maksymalnego czasu propagacji do 54%.
EN
The paper deals with the problem of a binary comparator synthesis in CPLD/FPGA structures. The comparators were built with the usage of the Verilog language and the Quartus II graphics editor [10]. Section 1 describes the notion of a digital comparator, its basic usage [1-4] and research directions [6-10]. Section 2 presents the general hierarchical structure of the comparator (Fig. 1). Section 3 describes the parallel-serial method of the comparator synthesis [10]. This method was used in the first level comparator synthesis in hierarchical structures of 128-bit and 256-bit comparators. Section 4 presents the results of experimental research. The comparators were built and tested in the Altera Quartus II environment. In the experimental investigations, hierarchical comparators (128-bit and 256-bit) were compared with the comparators (128_lpm and 256_lpm) built with the direct usage of the lpm_compare library function of the Quartus II package. The research was conducted on two CPLD families (MAX II and MAX V) and on four FPGA families (Cyclone III, Arria II GX, Arria V GZ and Stratix III). Two parameters, the implementation cost and the maximum propagation delay, were compared. For 128-bit comparators, the implementation cost was reduced by 13% and the maximum propagation delay was reduced up to 38% (depending on the family of FPGA structures). For 256-bit comparators, the implementation cost was reduced by 19% and the maximum propagation delay was reduced up to 54% (depending on the family of FPGA structures).
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