| 摘要 |
PROBLEM TO BE SOLVED: To achieve both spurious reduction and high frequency switching.SOLUTION: A local signal generator unit 21 includes a VCO 121, a DDS 123, an LPF 124, a reference signal generator 126, a phase comparator 125, and a loop filter 127. From combinations of preset values for a phase shift amount &Dgr;Φ and a reference frequency Fr of the DDS 123 required for a frequency Fb of a test signal S generated by a frequency converter unit 13 to be as specified by frequency designation means 14, a frequency control unit 25 selects a combination which results in a frequency of an input clock B to the DDS 123 being equal to P (integer of 3 or more) times a frequency of an output signal D of the DDS 123, and sets the combination to the DDS 123 and the reference signal generator 126. |
