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US 6,556,159 B1Granted
Variable order modulator
AssigneeCirrus Logic, Inc.
InventorsXiaofan Fei, Johann G. Gaboriau, John Laurence Melanson
Life of this patent
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Abstract
A delta-sigma modulator 400 includes circuitry 407 for selectively varying an order of the modulator to vary a modulation index of the delta sigma modulator.
Claims23
A delta sigma modulator comprising circuitry for selectively dynamically varying an order of the modulator in response to ramping a level of an input data stream.
A method for reducing discontinuities in a data stream output from a delta sigma modulator comprising the steps of:
- configuring the delta sigma modulator to have a low modulator order and a high modulation index;
- ramping-up an input signal to the delta sigma modulator up to a selected threshold to drive an output of the delta sigma modulator with the high modulation index;
- and
- reconfiguring the delta-sigma modulator after ramping the input signal to the threshold to increase the modulator order.
1 more element
An audio circuit comprising:
- a variable order delta-sigma modulator having a low order during ramp-up of a input signal level during power-up of the audio circuit and a higher order during normal mode processing of an audio data stream.
Dependencies are inferred from the claim text.