Patent ID: 8222935

Claim:
A communication system comprising: a phase-locked loop that maintains synchronization of a reception signal, wherein the phase-locked loop includes a loop filter that has a circuit configuration m for an m-th order phase-locked loop including a circuit configuration n for an n-th order phase-locked loop (m>n), and a switching section that switches circuit configurations, which are activated in the loop filter, between the circuit configuration n and the circuit configuration m; and a control section that controls the switching section to switch the circuit configurations in response to change in a current state of the communication system, wherein the control section compares a threshold value with a value which is obtained on the basis of signal intensity measurement of the reception signal, controls the switching section to switch the circuit configurations, which are activated in the loop filter, from the circuit configuration n to the circuit configuration m when the value is equal to or greater than the threshold value, and controls the switching section to switch the circuit configurations, which are activated in the loop filter, from the circuit configuration m to the circuit configuration n when the value is less than the threshold value.