Data converters with digitally filtered pulse width modulation output stages and methods and systems using the same
AssigneeCirrus Logic, Inc.
InventorJohn Laurence Melanson
Life of this patent
Estimating the term…
Abstract
A digital to analog converter including a noise shaping modulator for modulating an input digital data stream, a plurality of output elements for generating a plurality of intermediate data streams from a modulated output stream from the modulator, and an output summer for summing the intermediate data streams to generate an output analog stream. The noise shaping modulator balances an edge transition rate of the output elements, such that the edge transition rate of two selected elements is approximately equal.
Claims34
A digital to analog converter, comprising:
- a noise shaping modulator for modulating an input digital data stream;
- a plurality of output elements for generating a plurality of intermediate data streams from a modulated output stream from the modulator;
- an output summer for summing the intermediate data streams to generate an output analog stream;
- and
- wherein the noise shaping modulator balances an edge transition rate of the output elements such that the edge transition rate of two selected elements is approximately equal.
A data converter, comprising:
- a duty cycle modulator for converting a received data stream having a frequency into a duty cycle modulated data stream;
- and
- a finite impulse response filter for filtering harmonics of the frequency of the received data stream from the duty cycle modulated data stream.
A digital to analog converter, comprising:
- a noise shaper for generating a noise-shaped data stream at a first frequency;
- at least one pulse width modulator stage for generating from the noise-shaped data stream a pulse width encoded data stream at a second frequency of a selected multiple of the first frequency;
- output circuitry for converting the pulse width encoded data stream into an analog signal comprising:
- a finite impulse response filter for filtering the pulse width encoded data stream at a frequency greater than or equal to the second frequency;
- and
- a plurality of digital to analog conversion elements coupled to selected taps of the finite impulse response filter for generating an output analog signal.
A delta-sigma data converter, comprising:
- a delta-sigma modulator for quantizing received data into first and second quantized samples;
- and
- first and second interleaved output elements respectively operating on the first and second quantized samples to generate first and second output streams with balanced transition densities.
A method of data conversion, comprising:
- converting a data stream having a frequency into a duty cycle modulated data stream;
- and
- filtering harmonics of the frequency of data stream from the duty cycle modulated data stream with a finite impulse response filter.
A data converter, comprising:
- first and second noise shapers interleaved in time to noise shape corresponding portions of a stream of input data;
- and
- first and second finite impulse response filters respectively filtering output data streams from the first and second noise shapers.
A data converter comprising a signal input, a first and second duty cycle modulated signals responsive to the input signal, a first controllable current source responsive to the first duty cycle signal, a second controllable current source responsive to the second duty cycle signal, and a summer responsive to both controlled current sources.
Dependencies are inferred from the claim text.