Sample rate converters using virtual sample rates and analog to digital and digital to analog converters using the same
AssigneeCirrus Logic, Inc.
InventorsAnand Venkitachalam, Dylan Alexander Hester, Brian Frank Bounds, Rajendra Datar, Krishnan Subramoniam
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Abstract
A method of performing sample rate conversion in a data converter operating from an oversampling clock corresponding to a native sample rate and a native oversampling factor. A virtual sample rate and a virtual oversampling factor are selected proportional to the native sample rate and the native oversampling factor. A data stream having a data sample rate is sampled by the virtual oversampling factor. The data stream is also resampled with a resampling ratio approximating a ratio of the data sample rate to the virtual sample rate.
Claims20
A method of performing sample rate conversion in a data converter operating from an oversampling clock corresponding to a native sample rate and a native oversampling factor comprising the steps of:
- selecting a virtual sample rate and a virtual oversampling factor proportional to the native sample rate and the native oversampling factor of the data converter;
- sampling a data stream having data sample rate by the virtual oversampling factor;
- and
- resampling the data stream with a resampling ratio approximating a ratio of the data sample rate to the virtual sample rate.
An integrated sample rate and digital to analog converter operating at a selected oversampling rate corresponding to a native sample rate and a native oversampling factor comprising:
- oversampling circuitry for oversampling an input digital data stream of an input data sample rate by a virtual oversampling factor proportionate with the native oversampling factor;
- a resampler for resampling the oversampled data stream by a resampling ratio approximating a ratio of the input sample rate to a virtual sampling rate, the virtual sample rate proportionate with the native sample rate;
- and
- digital to analog conversion circuitry for converting the resampled data stream to analog at the oversampling rate.
An integrated analog to digital and sample rate converter comprising:
- a delta-sigma modulator for converting analog data into a stream of digital data and operating at an oversampling rate corresponding to a native sample rate and native oversampling factor;
- a resampler for resampling the stream of digital data with a resampling ratio approximating a ratio of an output sample rate to a virtual sample rate to generate a stream of digital data at the output sample rate, the virtual sample rate propotionate with the native sample rate;
- and
- down-sampling circuitry for down-sampling the resampled data stream by a virtual oversampling factor proportionate with the native oversampling factor.
Dependencies are inferred from the claim text.