A capacitor array unit connected to an oscillation circuit having a piezoelectric resonator, a variable-capacitance diode connected to said piezoelectric resonator in series thereto, and a fixed-connection capacitor having a predetermined electrostatic capacitance value and connected to said variable-capacitance diode in parallel therewith, said oscillation circuit outputting an oscillation signal of a predetermined oscillation frequency, said capacitor array unit comprising:
- a plurality of selective-connection capacitors having predetermined electrostatic capacitance values;
- a capacitor-connecting circuit for connecting a selective-connection capacitor selected from among said selective-connection capacitors to said fixed-connection capacitor in parallel therewith;
- and
- a capacitor array unit controller for controlling a capacitor array unit, the capacitor array unit controller, comprising:
- memory storing connection control data used in the control of selection between connection and non-connection of said selective-connection capacitors to said fixed-connection capacitor;
- and
- a connection control circuit for causing said memory to store said connection control data based on externally-given adjusting control data and for controlling said capacitor-connecting circuit in accordance with at least one of said adjusting control data and said connection control data, wherein said connection control circuit comprises a start-up control circuit which, when power supply is turned on, temporarily connects a preselected one of said selective-connection capacitors to said fixed-connection capacitor.