Synchronizing Circuit And Communication Interface Circuit

A synchronizing circuit comprising:

• a voltage-controlled oscillator that generates a predetermined clock signal as a clock signal having a frequency corresponding to a control voltage of a control voltage node;
• a loop filter coupled to the control voltage node;
• and
• a switch circuit that switches between a frequency locked loop and a phase locked loop, wherein
• the frequency locked loop includes a frequency phase comparator, the loop filter, and the voltage-controlled oscillator, and performs frequency synchronization between the predetermined clock signal and an input signal,
• the phase locked loop includes a phase comparator, the loop filter, and the voltage-controlled oscillator, and performs phase synchronization between the predetermined clock signal and the input signal, and
• the loop filter performs the first loop filter processing as the loop filter processing of first filter characteristics when the frequency locked loop is selected by the switch circuit, and performs the second loop filter processing as the loop filter processing of second filter characteristics different from the first filter characteristics when the phase locked loop is selected by the switch circuit.