| 摘要 |
PURPOSE:To obtain a frequency relation between an input and an output signal of a voltage controlled oscillator by constituting a phase locked loop of the voltage controlled oscillator, a frequency divider, a phase comparator and a low-pass filter and measuring a DC voltage of the filter while changing frequency dividing ratios. CONSTITUTION:When a voltage from a low-pass filter 13 is applied to an input terminal 4 of the voltage controlled oscillator (VCO) 1, a signal having a frequency fv is outputted to an output terminal 5. This signal is inputted to a frequency divider 10, where the signal is frequency-divided by fv/N and the result is inputted to the phase comparator 11, where the signal is compared with a frequency f0 of a reference frequency generator 12 to generate a DC voltage in response to the phase difference and the voltage is fed to an input terminal 4 of the VCO1 via the filter 13. The relation of frequency in this case is given as fv=Nf0. Thus, when the output voltage of the low pass filter 13 is measured by a voltmeter 8, the relation of the input voltage versus oscillated frequency of the VCO1 becomes known. |
