| 摘要 |
PROBLEM TO BE SOLVED: To acquire signals in three-frequency bands by reducing the number of oscillators, and to freely set the frequencies. SOLUTION: This frequency synthesizer is provided with oscillators 1 and 6 for outputting first and second oscillation signals, phase shifters 2 and 9 for outputting two sets of first and second signals, whose phases are different by 90 deg. each from the first and second oscillation signals, a mixer 4 to which one off the first and second signals are respectively inputted from the two sets of signals, a mixer 5 to which the other signals are inputted, and an adder 10 for adding the respective mixed signals outputted from the mixer 4 and the mixer 5. Also, this frequency synthesizer is provided with a phase-switching means 3 for switching the phase relation of the signals, to be inputted to the mixer 4 and the mixer 5, and an input validity/invalidity-switching means 8 for validating/invalidating the input of the second signals to the mixer 4 and the mixer 5. Then, the signal, having the same frequencies as those of the first oscillation signal or the signal with the sum or difference of the frequencies of the first oscillation signal and the frequencies of the second oscillation signal, is outputted from the adder 10. |
