US Patent 7899858 Filter circuit

The present invention provides a filter circuit which can eliminate single noise effectively and is relatively simple in circuit configuration. First and second absolute values of differences between one-clock-preceding output data and both of one-clock-preceding input data and two-clock-preceding input data are respectively calculated by subtracters. When the first absolute value<the second absolute value, a selector selects one-clock-preceding input data as the present output data. When the first absolute value≧the second absolute value, the selector selects two-clock-preceding input data as the present output data.