BINARY CALCULATING CIRCUIT

摘要

PURPOSE: To accelerate carry propagation and speed up calculation by changing the roles between a 2nd input signal and a carry-in input signal. CONSTITUTION: A 1st means 100A of an adder 2A generates an exclusive OR signal Ai(+)Ri-IS between a 1st input signal Ai and the carry-in signal Ri-1S and a 2nd means 200A execute the exclusive OR function between the signal Ai(+)Ri-1S and its complementary signal/(Ai(+)Ri-1S) and a 2nd input signal Bi and generates a result signal Si. Then a 3rd means 300A generates a carry- out signal RiS by a transmitting function consisting of two transmission gates controlled with the signal Ai(+)Ri-1S and its complementary signal/[Ai(+)Ri-1S]. Thus, the roles of the 2nd input signal Bi and carry-in signal Ri-1S are exchanged and the carry-out signal RiS is calculated by using the intermediate variable obtained by the exchanging, thereby greatly reducing the carry propagation delay of parallel-connected cells.