Patent ID: 6058407
Filing Date: 2000-05-02
Classification: H03H

Abstract:
A FIR (Finite Impulse Response) filter outputting an input signal shifted by 90.degree., comprising:a control signal generating means for generating a plurality of control signals delaying one fourth of a cycle each other due to receiving a signal from a second clock with double the reference frequency of a reference clock and for generating select signals having a phase opposite to both of the clocks;a shift register section including a plurality of shift registers for receiving data to shift;first multiplexer means including a first plurality of multiplexers for selecting each data from the shift register section;tab coefficient generating means for generating a tab coefficient of the filter,multiplying means including a plurality of multipliers for multiplying the selected data from the first multiplexer means by a coefficient of the tab coefficient generating means for providing a multiplication result output;a first data storage means including a first plurality of data storage units respectively for storing the multiplication result output from the multiplying means;second multiplexer means for outputting the data selected from one out of the first plurality of data storage units in the first data storage means;first adding means for adding the output data from the second multiplexer means;second data storage means including a second plurality of data storage units for storing the outputs data from the first adding means; andsecond adding means for adding the output data from the second data storing means.