Synchronizing signal generating device and method for serial communication
AssigneeDenso Corporation
InventorHisanori Miura
Life of this patent
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Abstract
A synchronizing signal generating device for serial communication is constructed with a reference clock circuit, a phase comparator, a PLL filter, VCO and a frequency dividing circuit. The PLL filter continually outputs an unchanged voltage signal when the phase differential signal is within a predetermined range determined by the upper and lower limit values of the phase difference. As a result, noise occurring in connection with variation of the frequency of a synchronizing signal every predetermined period is suppressed.
Claims5
A synchronizing signal generating device for serial communication comprising:
- a reference signal generating means for generating a reference signal having a predetermined frequency;
- a phase comparing means for comparing a phase of the reference signal with a phase of a feedback signal and outputting a phase differential signal corresponding to a phase difference between the phases;
- a frequency adjusting means for adjusting a frequency of a serial communication synchronizing signal to be output every predetermined period on the basis of the phase differential signal;
- and
- a feedback means for feeding back the serial communication synchronizing signal as the feedback signal to the phase comparing means,
- wherein the frequency adjusting means ceases to adjust the frequency of the serial communication synchronizing signal when the phase differential signal is between an upper limit value and a lower limit value of the phase difference.
A synchronizing signal generating method for serial communication comprising steps of:
- generating a reference signal having a predetermined frequency;
- comparing a phase of the reference signal with a phase of a feedback signal and outputting a phase differential signal corresponding to a phase difference between the phases;
- setting upper limit value and lower limit value of a phase difference of the reference signal and the feedback signal;
- adjusting a frequency of a serial communication synchronizing signal to be output every predetermined period on the basis of the phase differential signal only when the phase differential signal is outside a range defined by the upper limit value and the lower limit value;
- and
- feeding back the serial communication synchronizing signal as the feedback signal to the phase comparing means.
Dependencies are inferred from the claim text.