Patent ID: 6845135

Claim:
Apparatus for performing infinite impulse response filtering, the apparatus comprising: a first infinite impulse response filtering stage, the first filtering stage including one or more storage elements, the one or more storage elements being operative to store, in accordance with the filtering of a current input sample, one or more feedback state values associated with one or more input samples which precede the current input sample; and at least a second infinite impulse response filtering stage, the second filtering stage being operatively coupled to the first filtering stage and including one or more storage elements, the one or more storage elements being operative to store, in accordance with the filtering of the current input sample, one or more feedback state values associated with one or more input samples which precede the current input sample; and an intermediate storage element, the intermediate storage element being operatively coupled between the first filtering stage and the second filtering stage and operative to store, in accordance with the filtering of the current input sample, a partial state value useable to update at least one feedback state value associated with the second filtering stage for the filtering of a next input sample, the partial state value being a function of at least one feedback state value associated with the current input sample and the input sample preceding the current input sample.