Apparatus and method for generating small-size spread spectrum clock signal

A method comprising:

• generating a reference clock signal by dividing an external clock signal;
• detecting frequency and phase differences between the reference clock signal and a comparison clock signal as error signals, modulating a controlled voltage corresponding to a current in accordance with a modulation control signal, outputting an oscillation clock signal having a frequency oscillated according to the modulated controlled voltage as a spectrum-spread version of the external clock signal, and generating the comparison clock signal by dividing the oscillation clock signal;
• and then
• compensating for the modulation of the controlled voltage in accordance with a demodulation magnitude that is generated for use in compensating for a modulation magnitude.

A method comprising:

• generating a reference clock signal by dividing an external clock signal;
• detecting frequency and phase differences between the reference clock signal and a comparison clock signal and then outputting the detected frequency and phase differences as error signals;
• outputting current in accordance with the error signals;
• outputting a controlled voltage corresponding to the current;
• generating a modulation magnitude in accordance with a modulation control signal;
• modulating the controlled voltage in accordance with the modulation magnitude;
• outputting an oscillation clock signal having a frequency oscillated in accordance with the modulated controlled voltage as a spectrum-spread version of the external clock signal;
• generating the comparison clock signal by dividing the oscillation clock signal;
• generating a demodulation magnitude for use in compensating for the modulation magnitude;
• and then
• compensating for the modulation of the controlled voltage in accordance with the demodulation magnitude.