Patent attributes
A prescaler circuit includes: a frequency number switching part including first to sixth D-type flip-flop circuits, first and second AND circuits and first and second OR circuits; and a frequency division switching control part including a third AND circuit, a third OR circuit and first and second NOR circuits. The frequency number switching part has a function of controlling the frequency division among frequency division numbers of 1/N, 1/(N+1) and 1/(N+2) via the first and the second AND circuits by controlling modulus signals input to the first and the second NOR circuits. The frequency division switching control part has a function of controlling the frequency division between ⅛-frequency-division and 1/16-frequency-division by controlling a modulus signal input to the third AND circuit. A margin for a delay time that causes misoperation at the time of the switching of frequency division numbers can be increased.
