1. An equalizer comprising: an equalizer filter for processing an input sample data stream with filter coefficients to generate an equalized signal; a first multiplier for multiplying a scrambling code conjugate signal with the equalized signal to generate a descrambled equalized signal; an adder for generating an error signal by subtracting the descrambled equalized signal from a reference signal; an error filter for filtering the error signal to generate a filtered error signal; a tap coefficients generator for generating tap coefficients based on the filtered error signal for updating the filter coefficients of the equalizer filter; and a first down-sampler inserted between the equalizer filter and the first multiplier for down-sampling the equalized signal, wherein if the sample data stream undergoes over-sampling (OS), the equalized signal is down-sampled by the first down-sampler by a factor of OS.