Oscillator controller incorporating a voltage-controlled oscillator that outputs an oscillation signal at a desired oscillation frequency

An oscillator controller, comprising:

• a phase frequency detector that compares a reference signal and a frequency-divided signal and outputs a phase difference signal;
• a charge pump that outputs a phase error signal according to the phase difference signal output from said phase frequency detector;
• a loop filter that filters the phase error signal output from said charge pump and outputs an oscillation frequency controlling voltage;
• a voltage-controlled oscillator that has an LC resonator having a coil, a variable capacitor connected to the opposite end of the coil at the opposite ends thereof, and a capacitor connected in series with a switch between the opposite end of said variable capacitor, the oscillation frequency of the voltage-controlled oscillator being controlled through adjustment of the capacitance value of said variable capacitor by said oscillation frequency controlling voltage;
• a frequency divider that divides the frequency of the output of said voltage-controlled oscillator and outputs said frequency-divided signal;
• a first counter that counts the number of waves of said reference signal to a desired number and outputs a first flag signal;
• a second counter that counts the number of waves of said frequency-divided signal to said desired number and outputs a second flag signal;
• a first comparator that compares said first flag signal and said second flag signal and outputs a frequency comparison signal;
• and
• a control circuit that controls said voltage-controlled oscillator, said first counter, said second counter and said frequency divider by outputting signals thereto,
• a second comparator that receives a reference voltage and said oscillation frequency controlling voltage and outputs a signal synchronized with said reference signal;
• and
• a multiplexer that selects one of the output signal from the second comparator and the output signal from said phase frequency detector based on a selection signal from said control circuit and outputs the selected one to said charge pump.