To control only a phase while keeping the duty ratio of a generated pulse constant.

1st and 2nd HSAW generating circuits 11 and 12 generate two saw-tooth waves HSAW1 (B) and HSAW2 (F) in which amplitudes are fixed regardlessly of the frequency of a horizontal synchronizing signal HIN (A), the ratio of rising time and falling time is equal and phase difference is provided, and two pulses D and G are provided by slicing these two saw-tooth waves HSAW1 (B) and HSAW2 (F) at the slice level decided by a control voltage Vc at comparators 14 and 21. Then, these two pulses D and G are used as the set and reset inputs of a flip-flop 20. Thus, even when the slice level is changed, an output pulse fixed with the duty ratio and changed in only the phase is generated.