Switched capacitor filter
AssigneeStandard Microsystems Corporation
InventorCharles A. Lish
Life of this patent
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Abstract
A band-pass filter includes an arrangement of individual filter sections and means for weighting and summing the band-pass functions of the filter sections such that the active conjugate pole pairs are arranged in the z plane on a circle concentric to the unit circle and spaced by equal angles with the exception of corrector poles, which are spaced by half-angle increments from the adjacent poles. In the embodiment of the invention described, the filter sections are in the form of digitally controlled switched capacitor filters.
Claims6
A band-pass filter comprising an input terminal, a plurality of filter sections having predetermined transform functions and each having an input operatively connected to said input terminal, an output terminal, each of said plurality of filter sections comprising a switched capacitor filter including a plurality of switched capacitors, the values of the capacitances of said switched capacitances being selected so that each of said filter sections contributes one pair of conjugate poles to the overall filter transform function, and means operatively interposed between the outputs of said plurality of filter sections and said output terminal for selectively weighting and summing the outputs of said filter sections such that the active poles contributed by each of said filter sections are arranged on a circle concentric with and having a radius less than that of a unit circle of the z plane, said poles, with the exception of corrector poles, being equiangularly spaced from one another along said pole circle.
Dependencies are inferred from the claim text.