System and method for bandpass shaping in an oversampling converter
AssigneeLSI Logic Corporation
InventorJames S. Prater
Life of this patent
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Abstract
A digital filter in an oversampling converter is tuned to compensate for the non-ideal frequency response of a transducer coupled to the converter. In the A/D path, the filter coefficients of the decimation filter in a sigma-delta converter are tuned to compensate for the transducer. In the D/A path, the filter coefficients of the interpolation filter of a sigma-delta converter are tuned to compensate for the transducer. Filter coefficients may be statically defined in circuitry or programmable from values stored in a storage memory. Compensation may also be accomplished by tuning capacitor ratios in a switched capacitor filter, which is typically integral to the D/A path of an oversampling converter.
Claims27
A system for improving an effective frequency response of a transducer having a non-ideal transducer frequency response, said system comprising:
- an oversampling converter including a digital filter, an analog filter, a continuous time filer, and a modulator coupled to said transducer to shape quantization noise for conversion (i) from analog to digital signals and (ii) from digital to analog signals, at least one of said digital filter and said analog filter being tuned to compensate for said non-ideal transducer frequency response, wherein said continuous time filter is coupled to said modulator and said transducer for bandpass filtering an analog signal.
A system for improving an effective frequency response of a transducer having a non-ideal transducer frequency response, said system comprising:
- an oversampling converter including a digital filter including a bandpass digital filter, said digital filter having filter coefficients tuned to compensate for said non-ideal transducer frequency response and a modulator coupled to said transducer and said digital filter to shape quantization noise for conversion (i) from analog to digital signals and (ii) from digital to analog signals.
A system for improving an effective frequency response of a transducer having a non-ideal transducer frequency response, said system comprising an oversampling converter including an analog filter having at least one capacitor ratio tuned to compensate for said non-ideal transducer frequency response and a modulator coupled to said transducer and said analog filter shaping quantization noise for conversion (i) from analog to digital signals and (ii) from digital to analog signals, wherein a continuous time filter is coupled to said modulator and said transducer for filing an analog signal.
A method of improving an overall system frequency response of a transducer system, said method comprising the steps of:
- providing an oversampling converter configured to provide conversion (i) from analog to digital signals and (ii) from digital to analog signals including a digital filter coupled to a transducer having a transducer frequency response, wherein said converter includes a bandpass digital filter;
- and
- tuning at least one filter coefficient of said digital filter to compensate for said transducer frequency response.
A method of improving an overall system frequency response of a transducer system, said method comprising the steps of:
- providing an oversampling converter configured to perform conversion (i) from analog to digital signals and (ii) from digital to analog signals including an analog filter coupled to a transducer having a transducer frequency response, wherein said converter includes a digital filter, an analog filter, a modulator and a continuous time filter, wherein said continuous time filter is coupled to said modulator and said transducer for bandpass filtering an analog signal;
- and
- tuning at least one capacitor ratio in said analog filter to compensate for said transducer frequency response.
Dependencies are inferred from the claim text.