Abstract: The present invention relates in one aspect to a voice coil temperature protector for electrodynamic loudspeakers. The voice coil temperature protector comprises an audio signal input for receipt of an audio signal supplied by an audio signal source and a probe signal source for generation of a low-frequency probe signal. A signal combiner is configured to combine the audio signal with the low-frequency probe signal to provide a composite loudspeaker drive signal comprising an audio signal component and a probe signal component. The voice coil temperature protector comprises a current detector configured for detecting a level of a probe current component flowing through the voice coil in response to the composite loudspeaker drive signal and a current comparator which is configured to comparing the detected level of the probe current component with a predetermined probe current threshold.

Abstract: A method of estimating diaphragm excursion of an electrodynamic loudspeaker may be performed using audio signals. An audio output signal may be applied to a voice coil of the electrodynamic loudspeaker through an output amplifier to produce sound. A detected voice coil current and a determined voice coil voltage may be applied to a linear adaptive digital loudspeaker model that has a plurality of adaptive loudspeaker parameters. The parameter values of the adaptive loudspeaker parameters may be computed based on the linear adaptive digital loudspeaker model and applied to a non-linear state-space model of the electrodynamic loudspeaker. For the non-linear state-space model, a predetermined non-linear function may be applied to at least one of the plurality of received parameter values to compute at least one non-linearity compensated parameter value of the adaptive loudspeaker parameters, to determine an instantaneous excursion of the diaphragm.

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: 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 miniature loudspeaker may include a driver module with a flexible carrier having a proximal portion arranged within the perimeter of the frame and a distal portion arranged outside the perimeter of the frame, the flexible carrier carrying an output amplifier. The flexible carrier may be provided with electrically conductive traces connecting an amplifier input with input contact pads placed on the distal portion. The flexible carrier may be provided with electrically conductive traces connecting an amplifier output with output contact pads placed at the proximal portion. The output amplifier may be arranged on the proximal portion of the flexible carrier within the perimeter of the frame. The proximal portion of the flexible carrier may be rigidly attached to the static part. The output contact pads may be connected with the voice coil through flexible lead wires.

Abstract: A sensor polling unit for microprocessor integration comprises a configuration logic block associated with each of a plurality of external sensor devices. Each configuration logic block issues a read command for predetermined sensor data registers of the associated external sensor device via a read trigger supplied by a trigger generator. A global timer based on a microprocessor clock signal supplies a global time value to the trigger generators. A polling state machine is operatively coupled to the configuration logic blocks for receipt of respective read commands, and issues a corresponding read command to the external sensor device through a standardized bi-directional data communication interface connected to the external sensor device. The polling state machine receives register data transmitted by the external sensor device in response to the read command and transmits the received register data to a microprocessor accessible data memory area for storage.

Abstract: A microphone circuit assembly for an external application processor, such as a programmable Digital Signal Processor, may include a microphone preamplifier and analog-to-digital converter to generate microphone signal samples at a first predetermined sample rate. A speech feature extractor is configured for receipt and processing of predetermined blocks of the microphone signal samples to extract speech feature vectors representing speech features of the microphone signal samples. The microphone circuit assembly may include a speech vocabulary comprising a target word or target phrase of human speech encoded as a set of target feature vectors and a decision circuit is configured to compare the speech feature vectors generated by the speech feature extractor with the target feature vectors to detect the target speech word or phrase.

Abstract: A datapath circuit may include a digital multiply and accumulate circuit (MAC) and a digital hardware calculator for parallel computation. The digital hardware calculator and the MAC may be coupled to an input memory element for receipt of input operands. The MAC may include a digital multiplier structure with partial product generators coupled to an adder to multiply a first and second input operands and generate a multiplication result. The digital hardware calculator may include a first look-up table coupled between a calculator input and a calculator output register. The first look-up table may include table entry values mapped to corresponding math function results in accordance with a first predetermined mathematical function. The digital hardware calculator may be configured to calculate, based on the first look-up table, a computationally hard mathematical function such as a logarithm function, an exponential function, a division function and a square root function.

Abstract: A semiconductor circuit comprising a digital circuit portion, which comprises a combinatorial logic block. The semiconductor circuit further comprises a scan chain for loading and applying a predefined digital test pattern to inputs of the combinatorial logic block. A bi-directional communication port is adapted for writing incoming data to an address space of the digital circuit portion. Scan control hardware comprises a plurality of individually addressable scan control registers which are mapped to the address space of the bi-directional communication port. A method of testing the digital circuit portion involves, using the scan chain, writing bit values to inputs of the individually addressable scan control registers, and reading bit values from at least one output of an individually addressable scan control register. The method and semiconductor circuit allow thorough testing and diagnosing of failing semiconductor devices, including core logic thereof, while mounted on a printed circuit board.

Abstract: The present invention relates to a switched mode voltage regulator circuit comprising a regulation loop coupled between the output voltage of the regulator and a switch driver. The regulation loop comprising an error signal generator supplying a digital error signal representative of a voltage difference between the output voltage and a reference voltage. The regulation loop further comprises a linear digital filter and a non-linear digital filter both coupled for receipt of the digital error signal and a digital summer coupled for receipt of linearly and non-linearly filtered digital error signals to provide a combined digital error signal. A digital pulse modulator is configured to generate the pulse width or pulse density modulated driver control signal in accordance with the combined digital error signal.

Abstract: The present invention relates to an integrated amplification circuit for a transducer signal comprising a semiconductor substrate. The semiconductor substrate comprises a signal limiting network comprising first and second parallel legs coupled between an input of a preamplifier and a first predetermined electric potential of the integrated amplification circuit. The first leg comprises a plurality of cascaded semiconductor diodes coupled to conduct current in a first direction through the limiting network and the second leg comprises a plurality of cascaded semiconductor diodes coupled to conduct current in a second direction through the limiting network. A current blocking member is configured to break a parasitic current path between an anode or a cathode of a semiconductor diode of the first leg or the second leg and the semiconductor substrate.

Abstract: The present invention relates to a driver circuit wherein upper and lower legs of a first driver comprise first and second sets of parellelly coupled semiconductor switches, respectively. A control circuit is configured to generate respective control signals for the first and second sets of parellelly coupled semiconductor switches to create a current path through the upper and lower legs during an overlap time period between state transitions of a driver output.

Abstract: The present invention relates to a DC bias voltage circuit comprising a DC bias voltage generator adapted to supply a first DC voltage. A low-pass filter has an input operatively coupled to the first DC voltage to produce a second DC voltage at a low-pass filter output. The low-pass filter comprises an adjustable switched capacitor resistor setting a cut-off frequency of the low-pass filter and a controller is adapted to controlling a resistance of the adjustable switched capacitor resistor.

Abstract: The present invention relates to an electret condenser microphone which comprises an exterior sidewall structure attached to a carrier. The exterior sidewall structure comprises a non-conductive base material carrying first and second electrical wiring patterns electrically connected to first and second electrical traces, respectively, of the carrier. A diaphragm holder, carrying a conductive microphone diaphragm is attached to the sidewall structure to establish electrical connection between a conductive microphone diaphragm and one of the first and second electrical wiring patterns of the sidewall structure. A conductive perforated backplate is arranged in spaced relationship to the conductive microphone diaphragm. The conductive perforated backplate is electrically connected to another one of the first and second wiring patterns of the sidewall structure.