Multimode filter

摘要

A multimode filter in an optical storage device is used for filtering an error signal and outputting a frequency signal. The multimode filter comprises a CLV and CAV mode filter and a switch. The CLV mode filter is used for filtering the error signal and extracting a narrow bandwidth signal, whereas the CAV mode filter is used for filtering the error signal and extracting a wide bandwidth signal. The switch is used for selecting either the CLV mode filter or the CAV mode filter according to the recording mode of the optical storage device.