Patent ID: 6166533
Filing Date: 2000-12-26
Classification: G01R

Abstract:
A spectrum analyzer for analyzing frequency spectrum of an input signal, comprising:a first frequency converter formed of a first frequency mixer, a first IF (intermediate frequency) filter connected to an output of the first frequency mixer and a first local signal oscillator connected to the first frequency mixer for providing a first local signal thereto to produce a first-IF signal, the first local signal oscillator having a YIG (yttrium-iron-garnet) resonator which is driven by a ramp signal, and the first frequency mixer being provided with the input signal to be analyzed in a first mode;a second frequency converter which receives the first IF signal and formed of a second frequency mixer, a second IF filter connected an output of the second frequency mixer and a second local signal oscillator connected to the second frequency mixer for providing a second local signal thereto to produce a second IF signal;a third frequency converter which receives the second IF signal and formed of a third frequency mixer, a third IF filter connected to the third frequency mixer and a third local signal oscillator connected to the third frequency mixer for providing a third local signal thereto to produce a third IF signal which is displayed as frequency spectrum of the input signal;a frequency divider for dividing a frequency of the first local signal by a factor of N;a frequency multiplier for multiplying a frequency of the third local signal;a fourth frequency mixer which is provided with a divided frequency signal from the frequency divider as a fourth local signal; anda fifth frequency mixer which mixes the input signal to be analyzed and a multiplied frequency signal from the frequency multiplier as a fifth local signal in a second mode and provides a frequency converted input signal to the fourth frequency mixer in the second mode;wherein, in the second mode, the fourth frequency mixer mixes the fourth local signal and the frequency converted input signal and provides a resultant IF signal to the third frequency converter.