Apparatus and method of filtering a signal utilizing recursion and decimation
First Claim
1. A digital signal filter bank device for filtering an external input signal to generate a filtered digital output signal, the device comprising:
- input signal selector means for selecting between the external input signal and a low-pass filtered feedback signal to provide a filter input signal;
filter bank means for receiving the filter input signal and for filtering the filter input signal to concurrently generate both a high-pass filtered signal and a low-pass filtered signal, the low-pass filtered signal including a low-pass filtered output signal and the low-pass filtered feedback signal; and
frequency band select means for receiving both the high-pass filtered signal and the low-pass filtered output signal directly from the filter bank means for generating the filtered digital output signal;
wherein the filter bank means includes means for applying a distributed arithmetic algorithm to the filter input signal to generate first and second summations of product terms respectively representing the high-pass filtered signal and the low-pass filtered signal; and
wherein the filter bank means further includes low-pass filter means for generating the low-pass filtered feedback signal using a decimated sampling rate.
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Abstract
Digital filter bank device that operates in a frequency-time hierarchically arranged, recursively fed back scheme based on the concept of decimation of a multi-speed-rate-operated system. The digital filter bank device operates in accordance with the computational requirement of summation of products for generating a filter output signal, and the computations are performed according to a software scheme based on a distributed arithmetic algorithm. The use of minimum hardware is enabled by a time-multiplexed scheme for both the implementation of the decimation and the distributed arithmetic principles of signal processing. The use of such a digital filter bank device results in a digital filter hardware architecture that has a significantly reduced semiconductor device die surface area.
31 Citations
33 Claims
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1. A digital signal filter bank device for filtering an external input signal to generate a filtered digital output signal, the device comprising:
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input signal selector means for selecting between the external input signal and a low-pass filtered feedback signal to provide a filter input signal; filter bank means for receiving the filter input signal and for filtering the filter input signal to concurrently generate both a high-pass filtered signal and a low-pass filtered signal, the low-pass filtered signal including a low-pass filtered output signal and the low-pass filtered feedback signal; and frequency band select means for receiving both the high-pass filtered signal and the low-pass filtered output signal directly from the filter bank means for generating the filtered digital output signal; wherein the filter bank means includes means for applying a distributed arithmetic algorithm to the filter input signal to generate first and second summations of product terms respectively representing the high-pass filtered signal and the low-pass filtered signal; and wherein the filter bank means further includes low-pass filter means for generating the low-pass filtered feedback signal using a decimated sampling rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. A method of filtering an external input signal to generate a filtered digital output signal, comprising the steps of:
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a. choosing between the external input signal and a low-pass feedback signal to select a filter input; b. filtering the filter input as a first summation of product terms according to a distributed arithmetic algorithm, to produce a high-pass filtered signal; c. filtering the filter input as a second summation of product terms according to the distributed arithmetic algorithm and at a decimated sample rate, to produce a low-pass filtered signal; d. performing a next selection of the filter input as in said step a, using the low-pass filtered signal as the low-pass feedback signal; and e. transmitting the high-pass filtered signal as the filtered digital output signal. - View Dependent Claims (27, 28, 29, 30, 31, 32)
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33. A method of operating a digital filter bank for filtering an external input signal to produce a filtered digital output signal, comprising the steps of:
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a. storing an initial product term; b. providing, the external input signal to a pole unit; c. adding the external input signal to the initial product term to obtain a pole signal; d. converting the pole signal to a sequence of serial bits to provide a serialized pole signal; e. addressing a first memory location according to zeroth order term bits of the serialized pole signal; f. addressing a second memory location according to zeroth order term bits of the serialized pole signal; g. providing zeroth order term data corresponding to the first memory location to the pole unit; h. providing zeroth order term data corresponding to the second memory location to a zero unit; i. addressing a first memory location according to first order term bits of the serialized pole signal; j. addressing a second memory location according to first order term bits of the serialized pole signal; k. providing the first order term data corresponding to the first memory location to the pole unit; l. dividing the zeroth order term data provided to the pole unit a designated number of times to obtain a division result and adding the division result to the first order term data provided to the pole unit, to obtain a new pole signal; m. providing the first order term data corresponding to the second memory location to the zero unit; n. dividing the zeroth order term data provided to the zero unit a designated number of times to obtain a division result and adding the division result to the first order term data provided to the zero unit to obtain filtered signal data; o. adding the new pole signal to the filtered signal data; and p. repeating the steps a through n until N-1 ordered terms have been produced and added, wherein N is a predetermined number.
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Specification