Novel efficient digital microphone decimation filter architecture
AssigneeCreative Technology, Ltd.
InventorDavid Philip ROSSUM
Life of this patent
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Abstract
A new and more efficient filtering system (e.g., digital microphone decimation filter architecture system) is described. A key to this architecture is the use of two parallel filter paths. Each path operates at the output sample rate, and comprises a shorter FIR filter followed by a series of allpass stages (e.g., implementing IIR filters). The FIR filter is designed to remove all but the last octave of out-of-band noise. The allpass stages are designed such that when the two paths are summed together, the out-of-band noise for the final octave cancels out, leaving only the desired sign
Claims20
A filtering system for processing an input signal, comprising:
- an input interface operable to receive the input signal in a bitstream;
- a filtering module operable to process the input signal through a parallel circuit of filters, wherein the processing is performed using a single sample rate;
- and
- an output interface operable to generate an output signal based on the processed input signal.
A method for processing an input signal with a filtering system, comprising:
- receiving the input signal in a bitstream;
- processing the input signal through a parallel circuit of filters, wherein the processing is performed using a single sample rate;
- and
- generating from the filtering system an output signal based on the processed input signal.
Dependencies are inferred from the claim text.