Apparatus for noise shaping a pulse width modulation (PWM) signal and method therefor
Patent 6414613 Issued on July 2, 2002. Estimated Expiration Date: 
January 5, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
January 5, 2020. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesDigital correction circuit for data converters Digital converter Encoder signal analysis system for high-resolution position measurement Patent #: 5933106 InventorsAssigneeApplicationNo. 478013 filed on 01/05/2000US Classes:341/143, Differential encoder and/or decoder (e.g., delta modulation, differential pulse code modulation)341/138NonlinearExaminersPrimary: JeanPierre, PeguyAttorney, Agent or FirmInternational ClassH03M 003/00AbstractA method for preserving phase information during quantization of pulse width modulation (PWM) signals used in power system applications. In one embodiment, a digital audio amplifier (12) implements a method of noise shaping, where the quantization error is used in coordination with a noise shaping filter (64) to remove the noise from the desired baseband of the output. A phase-preserving expression is used to provide additional information for generating the amplified output (40). In one embodiment, the filter (64) includes a series of integrators (70, 72), where non-linear integration terms are added at each stage of integration to provide the phase information. In one embodiment the filter is implemented in software to run on a digital signal processor, and in another the filter is implemented in a hardware accelerator.Other References
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