Patent ID: 8102908

Claim:
A waveform equalizing device for performing waveform equalization for an input signal and outputting the equalization result as an output signal, comprising: an FIR (finite impulse response) filter for performing convolution operation between the input signal and a plurality of tap coefficients and outputting a result; first and second slicers, one of the first and second slicers making decision on a value of the output signal and outputting a result of the decision, and the other one of the first and second slices outputting the output signal without making the decision; a first delay device for imparting a delay to an output signal of the second slicer and outputting a resultant signal; an IIR (infinite impulse response) filter; an addition section for summing the result output from the FIR filter and an output of the IIR filter and outputting the sum as the output signal; an error detection section for detecting an error in the output signal and outputting a detection result as error information; and a tap coefficient updating section for updating tap coefficients for the FIR filter and the IIR filter based on the error information, wherein the IIR filter comprises: a first delay portion for receiving an output signal of the first slicer, imparting delays to the received output signal, and outputting a plurality of resultant signals via a plurality of taps, the delays being not more than a first delay and different from one another; and a second delay portion for receiving the resultant signal output from the first delay device, imparting delays to the received resultant signal, and outputting a plurality of resultant signals via a plurality of taps, the delays being not more than a second delay and different from one another, the IIR filter performs convolution operation between the received output signal received by the first delay portion and tap coefficients corresponding to the plurality of taps of the first delay portion and between the received resultant signal received by the second delay portion and tap coefficients corresponding to the plurality of taps of the second delay portion, and outputs an IIR result, and the first delay device imparts a delay so that a delay of the resultant signal output from the first delay device with respect to the output signal is equal to a delay of a signal having the largest delay among the delays imparted by the first delay portion with respect to the output signal.