Bandpass delta-sigma analog-to-digital converters
AssigneeLucent Technologies Inc.
InventorsUt-Va Koc, Jaesik Lee
Life of this patent
Estimating the term…
Abstract
An apparatus includes a delta-sigma analog-to-digital converter for digitalizing an analog input signal. The Δ-Σ ADC includes an analog band-pass loop filter configured to filter an analog signal derived from the analog input signal and a quantizer configured to produce a series of digital signals by sampling the filtered analog signal from the loop filter at a sampling frequency. The loop filter has a center band-pass frequency. The series of digital signals has a data-carrying frequency spectrum that is a mirror image of a data-carrying frequency spectrum of the analog input signal. The data-carrying frequency spectrum of the series is located between the center band-pass frequency and zero.
Claims15
An apparatus comprising:
- a delta-sigma analog-to-digital converter for converting an analog input signal, comprising:
- an analog band-pass loop filter configured to filter an analog signal derived from the analog input signal, the loop filter having a center band-pass frequency;
- and
- a quantizer configured to produce a series of digital signals by sampling the filtered analog signal from the loop filter at a sampling frequency, wherein the series of digital signals has a data-carrying frequency spectrum that is a mirror image of a data-carrying frequency spectrum of the analog input signal, the data-carrying spectrum of the series being located between the center band-pass frequency and zero;
- and
- a digital-to-analog converter configured to generate a series of the analog feedback signals at the sampling frequency such that each analog feedback signal has a duty cycle of less than ½ and corresponds to one of the digital signals.
A method, comprising:
- transmitting an analog input signal having a data-carrying band to a delta-sigma analog-to-digital converter to convert the analog input signal into a series of digital signals having a data-carrying band;
- filtering a modified analog signal with a loop band-pass filter having a center band-pass frequency;
- and
- wherein the series of digital signals has a data-carrying frequency spectrum that is a mirror image of a data-carrying frequency spectrum of the analog input signal, the data-carrying spectrum of the series being located between the center band-pass frequency and zero;
- performing digital-to-analog conversions of the digital signals to sequentially produce analog feedback signals with duty cycles of less than ½;
- and
- producing the modified analog signal filter by sequentially combining the analog feedback signals with the analog input signal.
Dependencies are inferred from the claim text.