Signal processing circuit having a voltage controlled oscillator capable of continuously changing the center frequency in accordance with a control voltage

A read apparatus comprising:

• a disk motor control circuit which rotates a disk;
• a pickup circuit which reads data from the disk;
• a data slice circuit which binarizes the read data and generates binarized data;
• a PLL circuit receiving the binarized data and having a voltage controlled oscillator which controls an output frequency in accordance with a first control voltage associated with the binarized data, and which is capable of controlling a center frequency in accordance with a second control voltage as an analog signal;
• and
• wherein when the output frequency is changed by the first control voltage, the center frequency is changed by the second control voltage.

A signal processing circuit comprising:

• a data slice circuit which binarizes data read from a disk and generates binarized data;
• a controller for generating a control instruction as a digital signal;
• a PLL circuit receiving the binarized data and having a voltage controlled oscillator which controls an output frequency in accordance with a first control voltage associated with the binarized data, and which is capable of controlling a center frequency in accordance with a second control voltage as an analog signal;
• a converter for converting the control instruction into the second control voltage;
• and
• wherein the output frequency is changed by the first control voltage and the center frequency is changed by the second control voltage.

A read apparatus comprising:

• a disk motor control circuit which rotates a disk;
• a pickup circuit which reads data from the disk;
• a data slice circuit which binarizes the read data and generates binarized data;
• a controller for generating a control instruction as a digital signal;
• a PLL circuit receiving the binarized data and having a voltage controlled oscillator which controls a output frequency in accordance with a first control voltage associated with the binarized data, and which is capable of controlling a center frequency in accordance with a second control voltage as an analog signal;
• a converter for converting the control instruction into the second control voltage;
• and
• wherein the output frequency is changed by the first control voltage and the center frequency is changed by the second control voltage.