Abstract: A multi-channel audio playback apparatus including a channel interface, a first switching amplifier and a second switching amplifier is provided. The channel interface is used to receive multi-channel digital data and generate first channel digital data and second channel digital data. The first switching amplifier is used to convert the first channel digital data into a first pulse width modulation (PWM) signal according to a first reference signal with a first frequency. The second switching amplifier is used to convert the second channel digital data into a second PWM signal according to a second reference signal with a second frequency. The second frequency is different from the first frequency.

Abstract: A microphone module includes a cabinet, a sensor, an integrated circuit chip, a first substrate, and a second substrate. The first substrate carries the integrated circuit chip and includes a first top surface, a first bottom surface, and a first shielding part with a fixed electric potential extending from the first top surface to the first bottom surface. The second substrate includes a second top surface contacting the first bottom surface, a second bottom surface, and a second shielding part with the fixed electric potential on the second bottom surface, wherein the second shielding part is arranged in such a way that no electromagnetic waves can pass between the first shielding part and the second shielding part.

Abstract: A micro-electro-mechanical-system microphone package includes a substrate, a micro-electro-mechanical-system microphone chip mounted on the substrate, and a cover attached to the substrate to cover the micro-electro-mechanical-system microphone chip. The cover is provided with a sound inlet through which the micro-electro-mechanical-system microphone receives external sound. The micro-electro-mechanical-system microphone chip includes a conductive base connected to a constant voltage, a shielding layer supported by the conductive base and connected to the constant voltage, a diaphragm disposed between the conductive base and the shielding layer, and a back plate also disposed between the conductive base and the shielding layer.

Abstract: An isolated feedback system for power converters includes an error amplifier for receiving an input voltage to output an error signal; a modulator circuit to modulate the error signal with a carrier signal; an acoustic transformer unit, one end of the acoustic transformer connected to the modulator circuit, where a frequency of the carrier signal is away from resonant frequencies of the acoustic transformer; and a demodulation circuit connected to the other end of the acoustic transformer and receiving the modulated signal.

Abstract: The invention provides an integrated circuit of a microphone. In one embodiment, the integrated circuit receives a first signal converted from a sound and receives a reference signal with a digital format for echo cancellation. In one embodiment, the integrated circuit comprises a pre-amplifier, an analog-to-digital converter, a digital signal processor, and a post amplifier. The pre-amplifier amplifies the first signal according to a first gain to obtain a third signal. The analog-to-digital converter converts the third signal from analog to digital to obtain a fourth signal. The digital signal processor cancels an echo component from the fourth signal according to the reference signal to obtain a fifth signal, and determines the first gain and a second gain, wherein a product of the first gain and the second gain is kept constant, and the first gain is determined so that an amplitude of the third signal is kept equal to an amplitude of the reference signal.

Abstract: An audio processing system is provided. The audio processing system comprises a transducer, a gain stage, a capacitor network, and a preamplifier. The transducer transduces a sound signal to a voltage signal. The gain stage comprises an input coupled to the transducer and an output. The capacitor network, coupled between the output of the gain stage and the transducer, provides an equivalent capacitance. The preamplifier coupled to the transducer amplifies the voltage signal.

Abstract: The invention provides an interfacing circuit for a removable microphone. In one embodiment, the interfacing circuit comprises a jack for receiving the removable microphone and an integrated circuit comprising a biasing circuit, a buffer amplifier, and an insertion detecting circuit. The jack comprises a first terminal receiving an output voltage of the removable microphone and a second terminal coupling the removable microphone to a ground voltage source. The integrated circuit is coupled to the first terminal of the jack via a first node. The biasing circuit, coupled between the first node and a second node, biases the removable microphone and passes only an alternative current (AC) portion of the output voltage of the removable microphone to the second node. The buffer amplifier, coupled to the second node, buffers the AC portion to generate a voltage signal.

Abstract: The invention provides a microphone. The microphone receives a first sound signal and at least one second electrical signal and outputs a third electrical signal. In one embodiment, the microphone comprises a transducer and a signal processor. The transducer converts the first sound signal to a first electrical signal. The signal processor has a first input terminal receiving the first electrical signal and at least one second input terminal receiving the at least one second electrical signal, and derives the third electrical signal from the first electrical signal and the second electrical signal. In one embodiment, the at least one second electrical signal is derived from a t least one second sound signal by at least one second microphone located in the vicinity of the microphone. In another embodiment, the at least one second electrical signal comprises a wind noise signal derived from wind pressure by a pressure sensor located in the vicinity of the microphone.

Abstract: The invention provides an audio interface device and method to acquire audio signal from either an analog or digital microphone through a common connector. The audio interface comprises a connector, electrically connected with a microphone plugged thereinto, an analog readout circuit, acquiring an analog audio signal from an analog microphone, a digital readout circuit, acquiring a digital audio signal from a digital microphone, and a decision circuit, selectively connecting the analog or digital readout circuit to the connector to acquire the analog or digital audio signal respectively according to whether the microphone plugged into the connector is analog or digital.

Abstract: A phase lock loop (PLL) circuit is provided. A voltage controlled oscillator (VCO) generates an output clock signal based on a control voltage. A controller provides a first digital control word, a second digital control word and a loop factor. A frequency modifier is coupled to the output clock signal, controlled by the controller to divide the output clock signal by the loop factor to generate a feedback frequency. A charge pump is controlled by the up signal and down signal to generate a charge pump current, comprising a first digital to analog converter (DAC) to generate a first current based on the first digital control word when the up signal is asserted. A second DAC generates a second current based on a second digital control word when the down signal is asserted. The controller defines a first relationship between the first digital control word and the loop factor, and the controller defines a second relationship between the second digital control word and the loop factor.

Abstract: The invention provides a microphone circuit. In one embodiment, the microphone circuit comprises a transducer, a biasing resistor, a pre-amplifier, and a switch circuit. The transducer is coupled between a ground and a first node for converting a sound into a voltage signal output to the first node. The biasing resistor is coupled between the ground and the first node. The pre-amplifier is biased with a biasing voltage and coupled between the first node and a second node, and amplifies the voltage signal to obtain an output signal at the second node. The switch circuit is coupled between the first node and the ground, couples the first node to the ground when the microphone circuit is reset, and decouples the first node from the ground after a voltage status of the microphone circuit is stable, thus clamping a voltage of the first node to the ground to prevent generation of a popping noise when the microphone circuit is reset.

Abstract: An audio processing circuit is provided, receiving a microphone signal from a microphone to output a differential signal. A preamplifier receives the microphone signal to output a first preamplified voltage and a second preamplified voltage. A gain stage receives the first preamplified voltage and the second preamplified voltage to output the differential signal comprising a first differential output and a second differential output. In the preamplifier, a first operational amplifier is provided. A first voltage controlled current source is controlled by the output end of the first operational amplifier to provide a first current. A first transistor has a gate coupled to a ground voltage supply, a source coupled to the first voltage controlled current source for receiving the first current, and a drain coupled to a voltage ground. Likewise, a second voltage controlled current source and a second transistor are presented symmetrically to render the differential output.

Abstract: A phase lock loop (PLL) circuit is provided. A voltage controlled oscillator (VCO) generates an output clock signal based on a control voltage. A controller provides a first digital control word, a second digital control word and a loop factor. A frequency modifier is coupled to the output clock signal, controlled by the controller to divide the output clock signal by the loop factor to generate a feedback frequency. A charge pump is controlled by the up signal and down signal to generate a charge pump current, comprising a first digital to analog converter (DAC) to generate a first current based on the first digital control word when the up signal is asserted. A second DAC generates a second current based on a second digital control word when the down signal is asserted. The controller defines a first relationship between the first digital control word and the loop factor, and the controller defines a second relationship between the second digital control word and the loop factor.

Abstract: An audio apparatus is provided, receiving a reference voltage and an input signal to generate an output signal. In the audio apparatus, a compensation circuit, generates a compensated reference voltage based on the input signal, the reference voltage and the output signal. A class AB power amplifier receives the compensated reference voltage to amplify the input signal into the output signal.

Abstract: An audio apparatus is provided, receiving a reference voltage and an input signal to generate an output signal. In the audio apparatus, a compensation circuit, generates a compensated reference voltage based on the input signal, the reference voltage and the output signal. A class AB power amplifier receives the compensated reference voltage to amplify the input signal into the output signal.

Abstract: A microphone array system and a method implemented therefore are provided. A first microphone having a first sensibility receives a sound source to generate a first signal. A second microphone is deposited at a distance from the first microphone, having a second sensibility for receiving the sound source to generate a second signal. A comparator subtracts the first signal and the second signal to generate a difference signal. An analyzer estimates an incident angle of the sound source to determine a compensation factor based on the first signal and the difference signal. A gain stage adjusts a gain of the difference signal based on the compensation factor to output an output signal.

Abstract: An MEMS microphone package includes a circuit board and an MEMS microphone chip. The MEMS microphone chip, mounted on the circuit board, includes a substrate, an MEMS transducer formed on the substrate, and a readout circuit also formed on the substrate. The MEMS transducer generates a sound signal according to sound pressure variations. The readout circuit reads the sound signal from the MEMS transducer.

Abstract: The invention provides an integrated circuit of a microphone. In one embodiment, the integrated circuit receives a first signal converted from a sound and receives a reference signal with a digital format for echo cancellation. In one embodiment, the integrated circuit comprises a pre-amplifier, an analog-to-digital converter, a digital signal processor, and a post amplifier. The pre-amplifier amplifies the first signal according to a first gain to obtain a third signal. The analog-to-digital converter converts the third signal from analog to digital to obtain a fourth signal. The digital signal processor cancels an echo component from the fourth signal according to the reference signal to obtain a fifth signal, and determines the first gain and a second gain, wherein a product of the first gain and the second gain is kept constant, and the first gain is determined so that an amplitude of the third signal is kept equal to an amplitude of the reference signal.

Abstract: A microphone preamplifier circuit is provided in a system on chip. An amplifier comprises a first input end, a second input end, and an output end. A bias voltage is provided by a bias voltage source. A first sensor is coupled to the first input end and the bias voltage source for sensing a first physical parameter and a second physical parameter. A second sensor is coupled to the second input end and the bias voltage source for sensing the first physical parameter, wherein the second sensor is insensitive to the second physical parameter. The output end of the amplifier outputs a difference of the first and second input ends whereby noises and interferences are reduced.

Abstract: A microphone preamplifier circuit is provided. An amplifier comprises a first input end, a second input end, and an output end. A bias voltage is provided by a bias voltage source. A first sensor is coupled to the first input end and the bias voltage source for sensing a first physical parameter and a second physical parameter. A second sensor is coupled to the second input end and the bias voltage source for sensing the first physical parameter, wherein the second sensor is insensitive to the second physical parameter. The output end of the amplifier outputs a difference of the first and second input ends whereby noises and interferences are reduced.