Method and arrangement for a sigma delta converter for bandpass signals

Claim 1

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio perforrmance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 2

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio perforrmance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 3

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulatin thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means further comprises amplifying means for amplifying the signal passing therethrough; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 4

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulatin thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means further comprises amplifying means for amplifying the signal passing therethrough; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 6

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus commprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means includes at least a single pole bandpass filter having a ringing frequency essentially equal to the non-zero carrier frequency; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 7

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus commprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means includes at least a single pole bandpass filter having a ringing frequency essentially equal to the non-zero carrier frequency; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 9

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output couple to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means includes a first and a second pole bandpass filter, with the second bandpass filter having a dual-zero phase compensation network therein in order to ensure loop stability; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 10

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output couple to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node, wherein said bandpass filtering means includes a first and a second pole bandpass filter, with the second bandpass filter having a dual-zero phase compensation network therein in order to ensure loop stability; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 14

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at at output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus, wherein said DC feedback means includes at least an integrator and a summing junction to further reduce qunatization error by minimizing any effects of DC offset voltages within the apparatus.

Claim 15

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at at output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus, wherein said DC feedback means includes at least an integrator and a summing junction to further reduce qunatization error by minimizing any effects of DC offset voltages within the apparatus.

Claim 16

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom, wherein said n-level quantizing means includes an A/D converter having n=2; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 17

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom, wherein said n-level quantizing means includes an A/D converter having n=2; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 19

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance, wherein said n-level D/A converting means comprises a D/A converter having n=2; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 20

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance, wherein said n-level D/A converting means comprises a D/A converter having n=2; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus.

Claim 22

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; further including a dither generator coupled to the second summing node and having a low-noise output at the non-zero carrier frequency due to an included bandreject filter centered thereat, said dither generator utilized to randomize quantization errors and to smooth an associated frequency spectrum of the error.

Claim 23

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; further including a dither generator coupled to the second summing node and having a low-noise output at the non-zero carrier frequency due to an included bandreject filter centered thereat, said dither generator utilized to randomize quantization errors and to smooth an associated frequency spectrum of the error.

Claim 24

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; wherein the improved signal-to-noise ratio performance allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 25

An apparatus for converting a signal having a non-zero frequency carrier or suppressed carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output from said quantizing means and having an output coupled to said first summing node, for converting said n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) direct current (DC) feedback means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; wherein the improved signal-to-noise ratio performance allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 26

An apparatus for converting a signal having a non-zero frequency carrier or suppressed with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; wherein any of said bandpass filtering means, said n-level quantizing means, said n-level D/A converting means, and said DC feedback means are constructed and arranged in dual differential form to provide further noise immunity and substantially reduced power requirements.

Claim 27

An apparatus for converting a signal having a non-zero frequency carrier or suppressed with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the apparatus comprising: (a) bandpass filtering means, having an input coupled to a first summing node, an output coupled to a positive input of a second summing node, and having an associated damped sinusoidal impulse response therein, for filtering the analog signal before applying it to the second summing node; (b) n-level quantizing means, having an input coupled to said second summing node, for quantizing the analog signal into a digital signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) n-level D/A converting means, having an input coupled to the output of said D/A converting means and an output coupled to a negative input of said second summing node, for feeding back a DC voltage to minimize DC offset voltages within the apparatus; wherein any of said bandpass filtering means, said n-level quantizing means, said n-level D/A converting means, and said DC feedback means are constructed and arranged in dual differential form to provide further noise immunity and substantially reduced power requirements.

Claim 28

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback to signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 29

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback to signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 30

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering and amplifying the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 31

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering and amplifying the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 32

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: bandpass filtering the analog signal supplied from a first summing node, and dithering the filtered analog signal by applying a dithered signal, having a bandreject characteristic centered at the non-zero carrier frequency to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 33

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: bandpass filtering the analog signal supplied from a first summing node, and dithering the filtered analog signal by applying a dithered signal, having a bandreject characteristic centered at the non-zero carrier frequency to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 34

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom, and wherein n=2; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.

Claim 35

A method for converting a signal having a non-zero frequency carrier with modulation thereon from an analog signal to a digital signal with improved signal-to-noise ratio performance, the method comprising the steps of: (a) bandpass filtering the analog signal supplied from a first summing node to provide a filtered signal to a second summing node; (b) quantizing the filtered analog signal by oversampling and providing a digital signal having a plurality of levels (n) at an output therefrom, and wherein n=2; (c) converting the n-level digital signal back to an analog signal to provide a negative feedback signal to the first summing node for providing improved signal-to-noise ratio performance; and (d) feeding back a DC voltage developed in step (c) to a negative input of said second summing node, to minimize DC offset voltages developed within the apparatus, said method providing improved signal-to-noise ratio performance which allows a dynamic range of approximately 95-98 dB to be achieved.