Abstract: A method of controlling sound reproduction may include applying an audio signal to a voice coil of the electrodynamic loudspeaker to produce sound, detecting one of an impedance and admittance of the loudspeaker across a predetermined audio frequency range based on a detected voice coil current and voice coil voltage and determining a fundamental resonance frequency of the loudspeaker based on the detected impedance or admittance. The fundamental resonance frequency of the loudspeaker may be compared with a nominal fundamental resonance frequency of the loudspeaker representing a nominal acoustic operating condition of the loudspeaker. A change of operating condition of the loudspeaker may be detected based on a frequency deviation between the determined fundamental resonance frequency and a nominal fundamental resonance frequency of the loudspeaker. The level of the audio signal may be attenuated in response to the frequency deviation meets a predetermined frequency error criterion.

Abstract: The invention may provide a temperature sensor device that includes an analog temperature sensor to generate a first base-emitter voltage and a second base-emitter voltage, and an analog-to-digital converter (ADC) to sample at the voltages and generate corresponding digital values. The temperature sensor device may also include a logic unit to calculate a digital temperature code from the digital values using a digital virtual reference.

Abstract: A method of detecting enclosure leakage of an electrodynamic loudspeaker mounted in an enclosure or box may include applying an audio signal to a voice coil of the electrodynamic loudspeaker through an output amplifier and detecting a voice coil current flowing into the voice coil. A voltage across the voice coil may be detected and an impedance or admittance of the loudspeaker across a predetermined audio frequency range may be detected based on the detected voice coil current and voice coil voltage. A fundamental resonance frequency of the loudspeaker may be determined based on the detected impedance or admittance and compared with a nominal fundamental resonance frequency of the loudspeaker representing a sealed state of the enclosure. Acoustic leakage of the enclosure may be detected based on a deviation between the determined the fundamental resonance frequency and the nominal fundamental resonance frequency of the electrodynamic loudspeaker.

Abstract: A method of detecting enclosure leakage of an electrodynamic loudspeaker mounted in an enclosure or box may include applying an audio signal to a voice coil of the electrodynamic loudspeaker through an output amplifier and detecting a voice coil current flowing into the voice coil. A voltage across the voice coil may be detected and an impedance or admittance of the loudspeaker across a predetermined audio frequency range may be detected based on the detected voice coil current and voice coil voltage. A fundamental resonance frequency of the loudspeaker may be determined based on the detected impedance or admittance and compared with a nominal fundamental resonance frequency of the loudspeaker representing a sealed state of the enclosure. Acoustic leakage of the enclosure may be detected based on a deviation between the determined the fundamental resonance frequency and the nominal fundamental resonance frequency of the electrodynamic loudspeaker.

Abstract: A method of controlling sound reproduction may include applying an audio signal to a voice coil of the electrodynamic loudspeaker to produce sound, detecting one of an impedance and admittance of the loudspeaker across a predetermined audio frequency range based on a detected voice coil current and voice coil voltage and determining a fundamental resonance frequency of the loudspeaker based on the detected impedance or admittance. The fundamental resonance frequency of the loudspeaker may be compared with a nominal fundamental resonance frequency of the loudspeaker representing a nominal acoustic operating condition of the loudspeaker. A change of operating condition of the loudspeaker may be detected based on a frequency deviation between the determined fundamental resonance frequency and a nominal fundamental resonance frequency of the loudspeaker. The level of the audio signal may be attenuated in response to the frequency deviation meets a predetermined frequency error criterion.

Abstract: The invention may provide a temperature sensor device that includes an analog temperature sensor to generate a first base-emitter voltage and a second base-emitter voltage, and an analog-to-digital converter (ADC) to sample at the voltages and generate corresponding digital values. The temperature sensor device may also include a logic unit to calculate a digital temperature code from the digital values using a digital virtual reference.

Abstract: Systems and method to compress digital video based on human factors expressed as a desirability score are provided. A particular method includes passing a digital input signal through a pulse-width modulator and passing an output of the pulse-width modulator through a power switching device. An output of the power switching device has a plurality of pulses. The method includes receiving the output of the power switching device at a first input of a comparator and receiving a reference voltage at a second input of the comparator. The method includes determining a net signal based on an output of the comparator and determining a timing error signal based on the net signal and the digital input signal. The method also includes adjusting the digital input signal to compensate for harmonic distortion based at least in part on the timing error signal.

Abstract: A digital timing read back and an adaptive feedforward compensation algorithm to reduce harmonic distortion is disclosed. More specifically, the approach generates harmonic components digitally with the same magnitude but at an opposite phase to the output harmonic distortion. An anti-distortion signal is generated and added to the input signal. The magnitude and phase of the harmonic distortion change with the modulation level or index and the frequency of the input signal. In addition, the harmonic distortion level varies significantly with different timing error statistics in different power devices. The inventive method takes the modulation level or index, the frequency of the input signal and the timing error statistics acquired through a digital read back circuit as input variables to determine the magnitude and phase of the anti-distortion signal.

Abstract: Apparatus and methods for reducing radio frequency interference produced by switching amplifiers, includes a variable-order noise shaper in a system that includes an AM tuner. An alternative implementation involves determining the tuned frequency of a radio signal. A first sampling rate is provided at which the radio signal is to be sampled. The first sampling rate is associated with a plurality of first harmonic frequencies. A second sampling rate is also provided and is associated with a plurality of second harmonic frequencies different than the first harmonic frequencies. The method involves selectively sampling the radio signal at one of the first and second sampling rates, wherein the first sampling rate is selected when the first harmonic frequencies do not coincide with the tuned frequency, and the second sampling rate is selected when the second harmonic frequencies do not coincide with the tuned frequency.

Abstract: A system and method for reducing distortion in a pulse width modulated digital system by selectively implementing linearization. The linearization is implemented computationally efficient, using no division operations. A frequency detector is implemented which causes signals to bypass the linearization algorithm at frequencies where the new modes of distortion become significant as a result of the linearization when used in combination with an interpolation filter.