| 摘要 |
PROBLEM TO BE SOLVED: To provide a frequency synthesizer without a spurious component. SOLUTION: The frequency synthesizer 1, that changes a frequency division value of a frequency divider so as to set a frequency of an external output signal OUT to a multiple of a mean frequency division value of a frequency of a reference clock signal, is provided with a reference automatic correction circuit 4 that measures a ripple component included in a control signal outputted from a charge pump circuit 35. A ripple correction circuit 39 generates a compensation current which is superimposed on a control signal to reduce the ripple component. While a negative feedback is formed to reduce the ripple component, a control circuit 55 obtains and outputs an optimum compensation current to the ripple correction circuit 39 to realize an output signal OUT without the spurious component. |
