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US 6,396,428 B1Granted
Continuous time bandpass delta sigma modulator ADC architecture with feedforward signal compensation
AssigneeRaytheon Company
InventorWilliam W. Cheng
Life of this patent
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Abstract
A continuous time Bandpass Delta Sigma (ΔΣ) Modulator architecture with feedforward and feedback coefficients to completely specify both the signal transfer function (STF) and the noise transfer function (NTF) for a stable modulator ADC system.
Claims13
An analog-to-digital converter system with a continuous time bandpass Delta Sigma (ΔΣ) modulator, for digitizing input signals of wide dynamic range, comprising:
- an nth order ΔΣ modulator, comprising a cascaded series of resonators, where n number of feedforward signals from the input signal are included to specify a prescribed signal transfer function to meet predetermined gain and/or phase characteristics, and
- said n number of feedforward signals have associated therewith N feedforward coefficients to realize a nth order signal transfer function.
An analog-to-digital converter system with a continuous time bandpass Delta Sigma (ΔΣ) modulator, for digitizing input signals of wide dynamic range, comprising:
- a cascaded series of resonators, where n number of feedforward signals from the input signal are connected through n feedforward signal paths to specify a prescribed signal transfer function to meet certain gain and/or phase characteristics, with N feedforward coefficients associated with the feedforward paths to realize a nth order signal transfer function;
- a quantizer circuit coupled to an output of a last one of said cascaded series of resonators to provide a digitized output corresponding to an analog input signal, the quantizer including a latching comparator;
- for each resonator, a first multi-bit quantizer digital-to-analog (DAC) in first feedback path from said digitized output to an input of the resonator, and a second multi-bit DAC in a second feedback path from said digitized output to said the resonator.
A method for digitizing an analog input signal, comprising:
- providing an nth order Delta Sigma modulator, comprising a cascaded series of resonators;
- providing n feedforward signal paths from the input signal to specify a prescribed signal transfer function to meet predetermined gain and/or phase characteristics, having associated therewith a corresponding feedforward coefficient to realize a nth order signal transfer function;
- applying the analog input signal to the n feedforward signal paths;
- quantizing an output of a last one of the cascaded resonators to provide a digital output.
1 more element
Dependencies are inferred from the claim text.