The invention provides a device and a method for generating a synchronous frequency dividing
clock in the
chip of a digital TV modulator. The invention is used in the
chip of the modulator for the
multimedia broadcasting base band of a GB20600 ground digital TV and able to divide the main frequency
clock signal exponentially. The device includes a main frequency
clock signal input end, a testing and enabling
signal input end, three basic frequency dividing units in serial connection and three selectors, and, in particular, two flip-latches. The device and the method divide the main frequency
clock signal into 2, 4 and 8 sections using a register and an
inverter, and meanwhile flip-latching the signal of divided frequency using the main frequency
clock signal; the obtained signal of divided frequency becomes the final
clock signal of divided frequency after passing through the selector. The invention has the main
advantage that each clock signal of divided frequency can be averaged according to the
delay in passing the main frequency clock signal so as to reduce the deflection of the synchronous clock signal, thus reducing the deflection of the clock of the whole
integrated circuit chip and improving the frequency and performance of the chip.