| 摘要 |
An adaptive sigma delta modulator has an input stage, a conventional sigma delta modulator, and adaptation stage, and an output stage. The input stage produces a difference signal representing the difference between an analog input signal and an adaptive signal, the amplitude of the analog input signal being in a first range [-a +a]. The conventional sigma delta modulator produces an intermediate digital output sequence representative of the difference signal, the amplitude of the intermediate digital output sequence being in a second range [-b +b], wherein b<a. The adaptation stage produces the adaptive feedback signal such that the amplitude of the adaptive signal keeps the difference signal within the second range [-b +b]. The output stage produces a final digital output sequence that is the sum of the intermediate digital output sequence and a delayed adaptive feedback signal representative of the adaptive feedback signal delayed by one sampling clock period. The final digital output sequence has an amplitude in the first range [-a +a] and is a digital representation of the analog input signal delayed by one sampling clock period.
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