Abstract: Systems and methods for detecting clipping conditions in an audio signal and processing the signal to reduce the clipping conditions. In one embodiment, a system comprises a noise shaper, a modulator, an output stage and other components. A detector detects clipping in the noise shaper and a signal processor processes the audio signal input to the noise shaper based on feedback received from the detector. The signal processor may function to modify the input audio signal in different ways in response to different conditions that are detected by the detector. A filter may be included to filter the output of the detector before being provided to the signal processor. A flag circuit may be coupled between the filter and the signal processor to assert an output signal until the signal processor resets the flag circuit.

Abstract: Systems and methods for converting a digital input data stream from a first sample rate to a second, fixed sample rate using a combination of hardware and software components. In one embodiment, a system includes a rate estimator configured to estimate the sample rate of an input data stream, a phase selection unit configured to select a phase for interpolation of a set of polyphase filter coefficients based on the estimated sample rate, a coefficient interpolator configured to interpolate the filter coefficients based on the selected phase, and a convolution unit configured to convolve the interpolated filter coefficients with samples of the input data stream to produce samples of a re-sampled output data stream. One or more hardware or software components are shared between multiple channels that can process data streams having independently variable sample rates.

Abstract: Two or more pulse width modulation stages, each having progressively higher resolution, are utilized to allow the lower resolution stage or stages to operate at lower clock speeds. Later stages are operated at higher clock speeds and thus a smaller portion of the total pulse width modulation circuit utilizes the higher clock speed. Additionally, later stages operate over smaller time intervals in order to reduce usage of the later stages.

Abstract: A digital input signal is modulated using multiple digital signal modulators operating at a variety of clock frequencies and clock frequency phase relationships to drive a load, such as an opposed current amplifier or other opposed current converter. The combinations of frequency relationships and digital signal modulator elements provide significant digital signal processing capabilities and flexible output signal timing. In one embodiment, a digital input signal, which may be biased, is modulated by multiple digital signal modulators to generate corresponding output signals. The corresponding output signals are utilized to drive a load, such as a half bridge, opposed current amplifier and to produce a single output signal. By adjusting the phase relationships between the clock frequencies, various output signal characteristics are achieved. Additionally, by utilizing digital signal processing to modulate the input signal, various processing technologies are applied to the input signal.

Abstract: A digital signal modulator modulates a digital input signal to drive a load, such as an opposed current amplifier or other opposed current converter. The combinations of frequency relationships and digital signal modulator elements provide significant digital signal processing capabilities and flexible output signal timing. In one embodiment, a digital signal modulator modulates a digital input signal. Even and odd samples of the input signal propagate along two respective channels (signal paths), which include further digital processing capabilities, such as pulse width modulation, to generate output signals appropriate for the topology of a load. Additionally, a bias signal may be modulated with the digital input signal. By utilizing digital signal processing to modulate the input signal, various processing technologies are applied to the input signal. For example, noise shaping may be implemented using a delta-sigma modulator as an input stage to the two channels.

Abstract: A digital signal modulator modulates a digital input signal to drive a load, such as an opposed current amplifier or other opposed current converter. The combinations of frequency relationships and digital signal modulator elements provide significant digital signal processing capabilities and flexible output signal timing. In one embodiment, a digital signal modulator modulates a digital input signal. Even and odd samples of the input signal propagate along two respective channels (signal paths), which include further digital processing capabilities, such as pulse width modulation, to generate output signals appropriate for the topology of a load. Additionally, a bias signal may be modulated with the digital input signal. By utilizing digital signal processing to modulate the input signal, various processing technologies are applied to the input signal. For example, noise shaping may be implemented using a delta-sigma modulator as an input stage to the two channels.