Multistage bandpass .DELTA. .SIGMA. modulators and analog-to-digital converters
AssigneeGeneral Electric Company
InventorsDavid B. Ribner, David H. K. Hoe
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Abstract
An architecture for oversampled delta-sigma (.DELTA.-.SIGMA.) analog-to-digital (A/D) conversion of high-frequency, narrow-band signals includes multistage .DELTA.-.SIGMA. modulators that incorporate band-reject noise shaping centered at one fourth the clock frequency Fs. These modulators cascaded with a bandpass digital filter also centered at a frequency of Fs/4 perform A/D conversion for high-frequency, narrow-band signals centered at the same frequency. The bandpass modulators are implemented by use of resonators in existing low-pass multistage modulators.
Claims15
An improved oversampling delta-sigma analog-to-digital converter system for high-frequency, narrow-band signals, said system having a plurality of delta-sigma modulator stages for providing respective digital output signals responsive to respective analog input signals, each of said modulator stages including an analog-to-digital converter and having a digital-to-analog converter in a feedback loop, said improved oversampling converter system comprising:
- a first resonator in each respective modulator stage situated to provide analog signals to said analog-to-digital converter in said stage and having a z transform transfer function ##EQU16## so as to enable said modulator stage;
- and means for combining the digital output signals of said plurality of delta-sigma modulator stages to suppress, in a resulting combined highly stable signal, quantization noise arising in at least one of said stages.
Dependencies are inferred from the claim text.