Fecha de publicación: 22/08/2002 Fuente: WIPO "royal booby" A counter circuit includes a plurality of flip flop circuits (FF circuits) sequentially connected for receiving a common clock signal, and two-input logic gates each having an input connected to an output of a corresponding FF circuit and the other input connected to an output of a common FF circuit, and of which output signal is supplied to an FF circuit positioned at the post stage of the corresponding FF circuit. A booby trap is realized by the two-input logic gates. The value input to each of the FF circuits is determined by logical operation of at most two logical values, so that the counter circuit can be adapted to the increasing frequency of a clock signal CLK. Thus, the counter circuit with the booby trap, capable of performing high-speed operation can be provided.