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A method of synthesis of two-level combinatorial circuits (method M3)

Many disadvantages of method M2 can be removed, if to fulfil mounting connection of outputs with the help of the second level PLD. The method of synthesis of two-level combinatorial circuits M3 consists of three stages. At the first stage set Y* of realizable functions is defined(determined); at the second stage the second stage of method M2 is fulfilled; at the third stage of a part of functions are united on OR with the help of the second level PLD. As in the two-level circuit each y_j funktion, y_j Y, is realized on a separate macrocell PLD for each function it is possible to select direct or inverse representation of the function, and required sort on an output to define(determine) by programming a logical level of an output signal of an output macrocell PLD.

Lowering of speed twice, in comparison with methods M1 and M2;
Magnification of cost of implementation, in comparison with method M2;
Various time of creation of values of the output functions realizable at the first and second levels of the circuit.

Thus, method M3 is intended for used, when method M2 is not applicable, for example, the digital system functions in positive logic, the PLD does not admit mounting connection of outputs, the stage of designer designing becomes complicated etc.

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