Finite impulse response filter
AssigneeMicroUnity Systems Engineering, Inc.
InventorAlan G. Corry
Life of this patent
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Abstract
A compact Finite Impulse Response (FIR) filter using one or both of a compact address sequencer and a compact multiplier/accumulator. The address sequencer exploits certain symmetry properties existing between different phases of a polyphase FIR filter in order to reduce coefficient storage and simplify address sequencing. The multiplier/accumulator is capable of performing two multiply/accumulate operations per clock cycle, avoiding in certain instances the need to add a second multiplier/accumulator. The area required to realize a FIR filter for performing real-time filter is therefore reduced.
Claims20
A method of calculating output data points of a polyphase Finite Impulse Response filter using a complex multiplier, comprising the steps of:
- a) applying to the complex multiplier a pair of constants K.sub.1 and K.sub.2 different from but related to a pair of filter coefficients A.sub.i and A.sub.j ;
- b) applying to the complex multiplier a pair of input operands X.sub.i and X.sub.j ;
- and
- c) operating the complex multiplier to form the quantity A.sub.i X.sub.i +A.sub.j X.sub.j.
A apparatus for calculating output data points of a digital filter comprising:
- a memory storing a plurality of filter-coefficient-related constants and for storing a plurality of input data points;
- an address generator connected to said memory;
- and
- a complex multiplier/accumulator connected to said memory and having a first input port, a second input port and an output port, said complex multiplier/accumulator receiving at said first input port signals representing a pair of constants different from but related to filter coefficients A.sub.i and A.sub.j, receiving at said second input port signals representing a pair of input data points X.sub.i and X.sub.j, and producing at said output port signals representing the quantity A.sub.i X.sub.i +A.sub.j X.sub.j.
Dependencies are inferred from the claim text.