Flexible and programmable delta-sigma analog signal converter
First Claim
1. A programmable delta-sigma analog signal converter comprising:
- an oversampling delta-sigma modulator for sampling and quantizing an input signal comprising a bandlimited signal at a carrier frequency to a single bit;
a serial-to-parallel converter coupled to the delta-sigma modulator;
a digital decimation filter for digitally filtering the signal output of the delta-sigma modulator to produce an estimate of the baseband in-phase and quadrature components of the input signal;
in-phase and quadrature video filters for processing the output of the decimation filter to generate in-phase and quadrature samples that are output from the analog signal converter; and
a plurality of digital-to-analog converters coupled to the delta-sigma modulator; and
a controller coupled to the plurality of digital-to-analog converters for centering noise shaping nulls of the delta-sigma modulator around the carrier frequency, for setting the spacing between noise shaping nulls to maximize the signal-to-noise ratio of the digital output of the analog signal converter, and coupled to the decimation filter to set the sample times of the filter to sample the carrier in quadrature and coupled to the decimation filter for programming the coefficients thereof to form a bandpass filter at the carrier frequency and coupled to the in-phase and quadrature video filters for programming the coefficients thereof to form bandpass filters at the decimated carrier frequency.
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Accused Products
Abstract
Processing apparatus is provided that directly samples and quantizes a complex envelope of a bandlimited waveform centered at a predetermined carrier frequency. An oversampling delta-sigma modulator 1 samples and quantizes the input signal to a single bit data stream. A serial-to-parallel converter converts the single bit data stream into a parallel bit stream. A digital decimation filter digitally filters the parallel bit stream to produce an estimate of the baseband in-phase and quadrature components of the input signal. In-phase and quadrature video filters generate in-phase and quadrature samples that are output from the analog signal converter. A controller 26 and a plurality of digital-to-analog converters 25 are used to center noise shaping nulls of the delta-sigma modulator around the carrier frequency. The controller sets the spacing between nulls of the serial-to-parallel converter to maximize the signal-to-noise ratio of the analog signal. The controller controls the decimation filter to set the sample times of thereof to sample the carrier in quadrature so that the coefficients are programmed to form a bandpass filter at the carrier frequency and programs the coefficients of the video filters to form bandpass filters at the decimated carrier frequency.
118 Citations
8 Claims
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1. A programmable delta-sigma analog signal converter comprising:
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an oversampling delta-sigma modulator for sampling and quantizing an input signal comprising a bandlimited signal at a carrier frequency to a single bit; a serial-to-parallel converter coupled to the delta-sigma modulator; a digital decimation filter for digitally filtering the signal output of the delta-sigma modulator to produce an estimate of the baseband in-phase and quadrature components of the input signal; in-phase and quadrature video filters for processing the output of the decimation filter to generate in-phase and quadrature samples that are output from the analog signal converter; and a plurality of digital-to-analog converters coupled to the delta-sigma modulator; and a controller coupled to the plurality of digital-to-analog converters for centering noise shaping nulls of the delta-sigma modulator around the carrier frequency, for setting the spacing between noise shaping nulls to maximize the signal-to-noise ratio of the digital output of the analog signal converter, and coupled to the decimation filter to set the sample times of the filter to sample the carrier in quadrature and coupled to the decimation filter for programming the coefficients thereof to form a bandpass filter at the carrier frequency and coupled to the in-phase and quadrature video filters for programming the coefficients thereof to form bandpass filters at the decimated carrier frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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Specification