Patent ID: 6138132
Filing Date: 2000-10-24
Classification: G06T

Abstract:
In a high speed ROM-based Nyquist FIR filter having a T-tap 1:N interpolation ratio and total N.times.2.sup.T/2N-1 -sized ROMs(Read Only Memories), the improvements comprising:a wave form generator for dividing an input clock signal and generating a control clock signal;shift registers connected in series with each other for shifting a data inputted in accordance with the control clock signal;a first multiplexer for crossingly selecting the output data shifted by the shift registers in accordance with the control clock signal;first exclusive OR circuits for selectively inverting an address of each ROM in accordance with the inverted control signal selected by the first multiplexers;two ROMs the size of each is half of the size of Nx2.sup.T/2N-1 in order to increase the number of outputs from the ROM;second exclusive OR circuits for selectively inverting an internal result with respect to a row of a coefficient matrix stored in each ROM in accordance with the inverted control signal selected by the first multiplexers;N/2 number of adders for receiving two groups of internal results which is concurrently read from each ROM selected by the second exclusive OR circuits and computing an N/2 number of series filter outputs at a time;an output register for temporarily storing the computed filter outputs;a third exclusive OR circuit for outputting a signal in order to sequentially select the filter outputs based on a logic combination of a control signal which is used for selecting a clock signal which is obtained by dividing a clock from the wave form generator and an output from the first multiplexer; anda second multiplexer for sequentially outputting filter outputs stored in the output register in accordance with a selection signal from the third exclusive OR circuit.