| 摘要 |
PURPOSE:To stably measure a frequency conversion circuit with high accuracy by connecting an LC tuning circuit section and a crystal oscillator in matching with a prescribed oscillation frequency of a local oscillation means and inputting an input signal with a predetermined constant frequency to a circuit to be measured. CONSTITUTION:Since the crystal oscillator 4 has the same natural oscillation frequency as a prescribed oscillating frequency of a local oscillator 22 and a high Q, while the tuning frequency of the LC tuning circuit section 3 is matched with the prescribed local oscillation frequency, in connecting the crystal oscillator 4 in parallel with the LC tuning circuit section 3, a stable prescribed local oscillation frequency with high accuracy is obtained regardless of the variation of the input impedance at an LC tuning circuit connection terminal 25 of the circuit 2 to be measured depending on each device. An input signal fed to an input terminal 24 of the circuit 2 to be measured from the signal source 1 and an output signal of the local oscillator 22 are mixed by a frequency converter, where the result is converted into an intermediate frequency signal. Then the electric characteristic such as an output voltage is measured by a measuring system 5.
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