| 摘要 |
An apparatus for calibrating the frequency of a VCTCXO(Voltage Controlled Temperature Compensated Crystal Oscillator) is provided to execute precisely frequency calibration by inputting merely a reference frequency signal to the VCTCXO. An apparatus(20) for calibrating the frequency of a VCTCXO includes the VCTCXO(200), a PLL(Phase Locked Loop) unit(210), a micro computer(230), a D/A(Digital to Analog) converter(250), a switching unit(220), and an A/D(Analog to Digital) converter(240). The PLL unit receives an output signal of the VCTCXO and a reference frequency signal from outside. The D/A converter receives a setting value from the micro computer, converts the inputted setting value into an analog signal, and outputs the converted analog signal. The switching unit selectively switches outputs of the PLL unit and the D/A converter, and inputs the switched signal to the VCTCXO. The A/D converter converts an analog signal, which is inputted to the VCTCXO by the switching unit, into a digital signal and the converted digital signal into the micro computer. |
