| 摘要 |
PURPOSE:To enable quick measurement even at a high frequency, by a method wherein a compound sinewave is converted to a high frequency with a second oscillator and a first mixer and reconverted to a low frequency with a third oscillator and second and third mixers to be inputted into a Fourier transform analyzer. CONSTITUTION:A first oscillator 7 generates a compound sinewave with the frequencies of 0-fA and a second oscillator 9 generates a signal with the frequency fB higher than the frequency fA and within a band to be measured. Outputs of the oscillators 7 and 9 are inputted into a first mixer 8, an output of which 8 is inputted into a circuit 2 to be measured and a third mixer 12. A third oscillator 10 generates a signal with the frequency of fB-fA and an output thereof is inputted into second and third mixers 11 and 12 and an output of the circuit 2 is inputted into the mixer 11. Outputs of the mixers 11 and 13 are inputted into LPFs 13 and 14, output of which are inputted into a Fourier transform analyzer 5. With the analyzer 5, the input signals is converted to digital signals by a Fourier transform to determine a gain phase thereof thereby enabling quick measurement even in a high frequency range.
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