Apparatus With Clock Generation Function, Method For Setting Reference Frequency, And Method For Adjusting Reference Frequency

An apparatus with a clock generation function comprising:

• an oscillator;
• storage means for data of a first frequency and data of a first level of voltage which is applied to the oscillator for generating a clock having the first frequency;
• normal operation mode oscillator controlling means for causing a clock having a required frequency to be generated by applying a voltage determined with reference to the first frequency and the first level to the oscillator during a normal operation;
• examination operation mode oscillator controlling means for causing a clock for examination by applying a voltage corresponding to the first level of voltage stored in the storage means to the oscillator;
• second frequency measuring means for measuring a second frequency of the clock for examination;
• adjustment operation mode oscillator controlling means for causing the oscillator to generate a clock for adjustment by applying a voltage corresponding to a second level of voltage for adjustment, the clock for adjustment being generated sequentially by varying the second level of voltage when a difference between the first frequency stored in the storage means and the second frequency measured by the second frequency measuring means is out of a predetermined range;
• third frequency measuring means for measuring a third frequency of the clock for adjustment generated by the oscillator;
• and
• reference level updating means for updating the data of the first level to data of the second level and storing the data of the second level when a difference between the third frequency and the first frequency is within a predetermined range.

A method for adjusting a reference frequency and a reference voltage level, the method applicable for an apparatus including an oscillator, a storage for storing data of the reference frequency and data of the reference voltage level of a voltage to be applied to the oscillator for causing the oscillator to generate a clock having the reference frequency, an oscillator controlling means for causing the oscillator to generate a clock having a required frequency by applying a voltage determined on the basis of the data of the reference frequency and the data of the reference voltage level to the oscillator, and a frequency counter for counting a frequency of a clock, the method comprising;

• generating a clock for examination by applying a voltage to the oscillator, the voltage being corresponding to the reference voltage level stored in the storage;
• measuring an examination frequency of the clock for examination generated by the oscillator;
• generating a plurality of clocks for adjustment by applying a voltage to the oscillator, the voltage being corresponding to an adjustment voltage level, the adjustment voltage level being varied when a difference between the reference frequency and the examination frequency measured by the frequency counter is out of a predetermined range;
• measuring a frequency of the clock for adjustment by the frequency counter;
• storing in the storage data of the adjustment voltage level instead of the data of the reference voltage level when a difference between the frequency of the clock for adjustment and the reference frequency is within a predetermined range.