FREQUENCY SYNTHESIZER HAVING LOW PHASE NOISE CHARACTERISTIC

摘要

PURPOSE: A frequency synthesizer having a low phase noise characteristic is provided to obtain an excellent phase noise characteristic in a high frequency band by applying multiple reference signals to a single loop structure. CONSTITUTION: A first reference signal source(11) provides a first reference signal. A second reference signal source(12) provides a second reference signal having a higher frequency than the first reference signal. A switching unit switches one of the first reference signal and the second reference signal. A voltage control oscillation unit outputs a high-frequency band signal which is generated from the first reference signal or the second reference signal. A phase fixing loop(20) fixes the phase of the high-frequency band signal which is outputted by the voltage control oscillation unit. A control unit(60) controls switching of the switching unit according to the size of the output frequency of the high-frequency band signal which is outputted by the voltage control oscillation unit. [Reference numerals] (AA) Output