Phase locked loop clock source provided with a plurality of frequency adjustments

An oscillator comprising:

• a piezoelectric resonator;
• an oscillation signal output section that oscillates the piezoelectric resonator and outputs an oscillation signal of a first frequency;
• a first programmable divider that divides the first frequency of said oscillation signal by a first frequency dividing number to obtain a reference signal of a second frequency;
• a PLL circuit section that receives said reference signal input thereto and obtains a multiplied signal of a third frequency, said PLL circuit section multiplying said input reference signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit to obtain said multiplied signal;
• and
• a setting section that variably sets said first frequency dividing number and said second frequency dividing, number to values independent of each other, said piezoelectric resonator being a rectangular AT cut quartz resonator that oscillates a fundamental wave of 25.1 MHz.

A frequency setting method for an oscillator comprising:

• measuring a resonant frequency of a piezoelectric resonator using a bypass circuit that directly outputs an oscillation signal without passing the oscillation signal through a first programmable divider and a PLL circuit section;
• outputting the oscillation signal of a first frequency by finely adjusting the resonant frequency of the piezoelectric resonator;
• outputting a reference signal of a second frequency by dividing the first frequency of the oscillation signal by a first frequency dividing number;
• operating a PLL circuit by using the reference signal as an input signal to the PLL circuit;
• forming a multiplied signal of a third frequency by multiplying said input signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit in the PLL circuit;
• setting, on a basis of sad resonant frequency unadjusted, said first frequency dividing number and said second frequency dividing number to numbers that said third frequency of the multiplied signal is obtained as a frequency closest to a desired frequency;
• and
• performing fine adjustment to adjust said third frequency equal to said desired frequency.

A frequency setting method for an oscillator comprising:

• outputting an oscillation signal of a first frequency by finely adjusting a resonant frequency of a piezoelectric resonator;
• outputting a reference signal of a second frequency by dividing the first frequency of the oscillation signal by a first frequency dividing number;
• operating a PLL circuit by using t he reference signal as an input signal to the PLL circuit;
• forming a multiplied signal of a third frequency by multiplying said input signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit in the PLL circuit;
• setting, on a basis of said resonant frequency unadjusted, said first frequency dividing number and said second frequency dividing number to numbers that said third frequency of the multiplied signal is obtained as a frequency closest to a desired frequency;
• and
• performing fine adjustment to adjust said third frequency equal to said desired frequency, setting said first frequency dividing number and said second frequency dividing number and performing fine adjustment being performed in a process of inspecting, by using probes, a circuit board on which said oscillator is mounted.

A frequency setting method for an oscillator comprising:

• measuring a resonant frequency of a piezoelectric resonator using a bypass circuit that directly outputs an oscillation signal without passing the oscillation signal through a first programmable divider and a PLL circuit section;
• outputting an oscillation signal of a first frequency by finely adjusting the resonant frequency of the piezoelectric resonator;
• outputting a reference signal of a second frequency by dividing the first frequency of the oscillation signal by a first frequency dividing number;
• operating a PLL circuit by using the reference signal as an input signal to the PLL circuit;
• forming a multiplied signal of a third frequency by multiplying said input signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit in the PLL circuit;
• setting, on a basis of an ideal resonant frequency of said piezoelectric resonator, said first frequency dividing number and said second frequency dividing number to numbers that said third frequency of the multiplied signal is obtained as a frequency closest to a desired frequency;
• and
• finely adjusting, on a basis of said first frequency dividing number and said second frequency dividing number obtained, said first frequency to a value that said desired frequency is obtained.

A frequency setting method for an oscillator comprising:

• outputting an oscillation signal of a first frequency by finely adjusting a resonant frequency of a piezoelectric resonator;
• outputting a reference signal of a second frequency by dividing the first frequency of the oscillation signal by a first frequency dividing number;
• operating a PLL circuit by using the reference signal as an input signal to the PLL circuit;
• forming a multiplied signal of a third frequency by multiplying said input signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit in the PLL circuit;
• setting, on a basis of an ideal resonant frequency of said piezoelectric resonator, said first frequency dividing number and said second frequency dividing number to numbers that said third frequency of the multiplied signal is obtained as a frequency closest to a desired frequency;
• and
• finely adjusting, on a basis of said first frequency dividing number and said second frequency dividing number obtained, said first frequency to a value that said desired frequency is obtained, setting said first frequency dividing number and said second frequency dividing number and performing fine adjustment performed in a process of inspecting, by using probes, a circuit board on which said oscillator is mounted.

A frequency setting system for an oscillator, said frequency setting system outputting an oscillation signal of a first frequency by finely adjusting a resonant frequency of a piezoelectric resonator, outputting a reference signal of a second frequency by dividing the first frequency of the oscillation signal by a first frequency dividing number, operating a PLL circuit by using the reference signal as an input signal to the PLL circuit to form a multiplied signal of a third frequency, the multiplied signal being obtained by multiplying said input signal by a second frequency dividing number from a second programmable divider provided in a feedback circuit in the PLL circuit, said frequency setting system comprising:

• a ROM that stores an amount of fine adjustment of the resonant frequency and said first frequency dividing number and said second frequency dividing number;
• probes attachable to a circuit board on which said oscillator is mounted;
• and
• a frequency setting apparatus that determines said fine adjustment amount and said first frequency dividing number and said second frequency dividing number through said probes, and sets the fine adjustment amount and said first frequency dividing number and said second frequency dividing number in said ROM.