Patent ID: 7555081

Claim:
A multi-rate filter system comprising: an input channel configured to receive an input signal; an output channel configured to output a filtered signal; a plurality of multi-rate filter sections coupled between the input channel and the output channel, at least one of the multi-rate filter sections comprising: a downsampler including a downsampler input and a downsampler output connected to a subsequent multi-rate filter section; a finite impulse response (FIR) filter channel coupled to the downsampler output, the finite impulse response (FIR) filter channel comprising: a real finite impulse response (FIR) filter interpolator; an imaginary finite impulse response (FIR) filter interpolator coupled in parallel with the real finite impulse response (FIR) filter interpolator; a real gain element coupled to the real finite impulse response (FIR) filter interpolator; and an imaginary gain element coupled to the imaginary finite impulse response (FIR) filter interpolator; a summer connected to the finite impulse response (FIR) filter channel; and an upsampler connected to the summer, the upsampler comprising an upsampler input and an upsampler output connected to either a prior multi-rate filter section or to an output signal summer.