Abstract: An aspect includes an apparatus including a first amplifier; a first field effect transistor (FET) including a first source coupled to an output of the first amplifier, and a first drain for coupling to a first load; and a first gate drive circuit including an input coupled to the output of the first amplifier and an output coupled to a first gate of the first FET. Another aspect includes a method including amplifying a first audio signal using a first audio amplifier to generate a first voltage; generating a first gate voltage based on the first voltage; applying the first gate voltage to a first gate of a first field effect transistor (FET) coupled between the first audio amplifier and a first audio transducer; and applying the first voltage to a first source of the first FET.

Abstract: A system includes a feedforward path coupled to a signal input. The system also includes a speaker coupled to the feedforward path. The system includes a back electromotive force (BEMF) extractor coupled to the speaker, where the BEMF extractor has a first input, a second input, and an output. The BEMF extractor includes a first summing point coupled to the first input. The BEMF extractor includes a resistor amplifier coupled to the second input and the first summing point. The BEMF extractor includes a high pass filter coupled to the second input and to an inductor amplifier. The BEMF extractor also includes a low pass filter coupled to the first summing point. The BEMF extractor includes a second summing point coupled to the low pass filter, the inductor amplifier, and the output.

Abstract: A power conversion system converts an input alternating-current voltage having a first frequency into an output alternating-current voltage having a second frequency lower than the first frequency. The power conversion system includes a voltage converter, a PDM controller, and a feedback controller. The voltage converter converts the input alternating-current voltage into the output alternating-current voltage in accordance with control signals and outputs the output alternating-current voltage to a load. The PDM controller performs pulse density modulation of an output voltage command value of the output alternating-current voltage to generate the control signals and outputs the control signals to the voltage converter. The feedback controller generates the output voltage command value based on an output current value of the voltage converter and a state of the load and outputs the output voltage command value to the PDM controller.

Abstract: A group of transistors is configured to drive a bus at time slots, to express data on the bus. The group of transistors dissipates an amount of electrical energy when driving the bus to a logic level opposite to a logic level present on the bus in an immediate preceding time slot. The group of transistors is arranged to dump another amount of electrical energy. Dumping of the other amount of electrical energy is responsive to driving the bus to a logic level that is the same as present on the bus in an immediate preceding time slot. The dumped amount of electrical energy is equivalent to the amount of energy dissipated by the transistors when transitioning the bus to a different logic level. Other aspects are also described.

Abstract: A semiconductor device includes a substrate having an opening extending through the substrate and at least one support member on a sidewall of the opening, a vibration membrane on the substrate, a cover layer on the vibration membrane. The substrate, the vibration membrane, and the cover layer define a cavity. The opening exposes a lower surface portion of the vibration membrane. The at least one support member on the sidewall of the opening provides support to the vibration membrane in a deformation of the vibration membrane to prevent breakage.

Abstract: Methods and apparatus for recalling and replaying content during a communications session are provided herein. In some embodiments, methods for replaying content during a communications session may comprise detecting a real-time communications session between two or more participant devices, storing content of the communications session transmitted between the two or more participant devices as the real-time communications session persists, receiving a control request from a first participant device of the two or more participants devices to replay a portion of the content; and transmitting the portion of the content to at least one of the participant devices as the real-time communications session persists.

Abstract: The application relates to a hearing device comprising a) first and second input transducers for picking up sound signals from the environment and providing first and second electric input signals, b) a first and signal strength detectors for providing signal strength estimates of the first and second electric input signal, the first input transducer being located at or behind an ear of the user, and the second input transducer being located at or in an ear canal of the user. The hearing device further comprises c) a signal processing unit providing a processed signal based on the first and second electric input signals, and d) an output unit comprising an output transducer for converting the processed signal or a signal originating therefrom to a stimulus perceivable by said user as sound.

Abstract: This application relates to methods and apparatus for determining the temperature of a voice coil of a loudspeaker (204), for instance as part of a system (208) for protecting the loudspeaker from overheating. The method comprises driving the voice coil with signal components at first and second frequencies, wherein the first frequency (fH) is higher than the second frequency (fL), and determining first and second indications of current (ICM) and voltage (VCM) of the voice coil at said first and second frequencies respectively. The method involves determining an estimated ratio value using the first and second indications of current and voltage, wherein said estimated ratio value corresponds to a ratio between a value based on the resistance of the voice coil and a value based on the inductance of the voice coil. The temperature of the voice coil is then determined based on said estimated ratio value and at least one reference value.

Abstract: An earbud sound system for a small speaker system having at least one earbud with a speaker and having, an earbud housing body defining a hollow interior a a circuit board within the housing body and having a signal input connection and a ground connection, and a speaker output connection and a speaker return connection; a bifilar coil unit having first and second coils wound in a bifilar manner, mounted on the circuit board within the housing body, and there being two first coil connections, and two second coil connections on the circuit board, for supporting the bifilar coil unit in a secure manner on the circuit board.

Abstract: A differential microphone with improved biasing and a well defined common mode output voltage is connected to an amplifier that includes a differential amplifier stage and a common mode feedback circuit. The amplifier is in a feedback configuration.

Abstract: A device and method are disclosed for modulating a power converter based on an audio signal to directly drive a speaker with a differential audio output signal. A first modulation signal and a second modulation signal are generated based on an input audio signal so that the first and second modulation signals are complementary signals to each other. In one embodiment, a feedback signal, such as an acoustic feedback signal from the speaker, is also used to generate the first and second modulation signals. A power supply voltage is modulated with the first modulation signal to generate a first voltage signal. The power supply voltage is also modulated with the second modulation signal to generate a second voltage signal. The first and second voltage signals form a differential audio signal that is used to drive the speaker. Alternatively, the power converter can drive a speaker with a single-ended output signal.

Abstract: An apparatus for providing an audio signal to drive a speaker system includes first and second audio channels. The first audio channel has a first class-D amplifier for receiving an input signal, and a first reconstruction filter for receiving an output from the first class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The second audio channel has a second class-D amplifier for receiving an input audio signal, and a second reconstruction filter for receiving an output from the second class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The first and second reconstruction filters have corresponding first and second planar inductors, with the second planer inductor being magnetically coupled to the first planar inductor.

Abstract: An audio amplifier receiving a digital input audio signal and generating an output audio signal for driving a speaker includes a digital input class D amplifier configured to receive the digital input audio signal and to generate the output audio signal. The digital input class D amplifier includes a first modulator configured to receive the digital input audio signal and to generate a quasi-digital signal in n-bit, and a class D modulator configured to receive the n-bit quasi-digital signal and to generate the output audio signal, the class D modulator implementing an analog feedback loop. In some embodiments, the class D modulator is implemented using a PWM modulator. In other embodiments, the PWM modulator incorporates enhanced features to improve the output noise characteristics.

Abstract: An audio output circuit includes an on-chip left channel amplifier module, an on-chip center channel amplifier module, and an on-chip right channel amplifier module. A left channel IC pin is operably coupled to an output of the on-chip left channel amplifier module. A right channel IC pin is operably coupled to an output of the on-chip right channel amplifier module. A center channel IC pin is operably coupled to an output of the on-chip center channel amplifier module. A center channel feedback IC pin is operably coupled to an input of the on-chip center channel amplifier module to provide a feedback loop. A left jack connection is operably coupled to the left channel IC pin. A right jack connection is operably coupled to the right channel IC pin. A jack return connection coupled to the center feedback IC pin. An inductor has a first node coupled to the jack return connection and a second node coupled to the center channel IC pin.

Abstract: A low-noise pre-amplifier with an active load element is integrated into a microphone. The microphone has an acoustic sensor coupled to the intrinsic pre-amplifier. A controllable current source is coupled to the intrinsic pre-amplifier and supplies a pre-amplifier bias current. A current source controller is coupled to the current source and controls the amplitude of the pre-amplifier bias current to maintain the intrinsic pre-amplifier at a bias point at which the intrinsic pre-amplifier amplifies microphone signals produced by the acoustic sensor. The intrinsic pre-amplifier may be actively regulated at the pre-determined bias point using negative feedback. Alternatively, the intrinsic pre-amplifier may be set to the pre-determined bias point by sweeping the pre-amplifier bias current for the intrinsic pre-amplifier over a range of currents.

Abstract: There is provided an audio amplifier circuit (200), comprising: an input, for receiving an input signal; an amplifier (205) for receiving a modified input signal and outputting an amplified signal; and a feedback loop (245) comprising digital circuitry for feeding back the amplified signal and combining a feedback signal with the input signal to generate the modified input signal. The feedback loop (245) comprises: a low-pass filter (220) for filtering the amplified signal; a comparator (225) for comparing the filtered signal with a threshold value and outputting a comparison signal; and an integrator (230) for integrating the comparison signal and outputting the feedback signal. According to another embodiment, the feedback loop comprises an integrator and a sigma-delta modulator.

Abstract: A dynamic sound enhancement system and method which produces non-linear dynamic gain, time domain offset, and damping control in relation to frequency components of an applied audio signal. The functions and characteristics of the system make it feasible to extend the ability of small speakers to distinctly reproduce natural low frequencies including bass and sub-bass frequencies concurrently with high frequencies. Further, the system provides customization of system characteristics for obtaining optimized sound quality, audibility, and sound perception from diverse sound producing devices, and which satisfies diverse user hearing needs and listening preferences.

Abstract: In an embodiment of the invention, the voice coil of an electro dynamic transducer is protected against thermal overload by estimating the temperature of a magnet in the electro dynamic transducer. When a power limit based on the temperature of the magnet and on a predetermined voice coil temperature limit is reached by an audio signal, the power applied to the voice coil is reduced.

Abstract: Audio transmitter circuitry is disclosed that is configurable into different modes by the user, and can output either a differential or single-ended audio signal on two signal wires. Depending on the mode, the transmitter deals with noise on the signal wires by adjusting the input resistance that such noise sees looking into the transmitter. If the transmitter is configured in a differential mode, the input resistance looking back into the transmitter from the perspective of the noise on both signal wires is relatively high. If the transmitter is configured in a single ended mode, the input resistance of noise looking back from the active signal wire into the transmitter is relatively low, to in effect ground such noise back into the transmitter, without significantly presenting such noise to the receiver.

Abstract: An apparatus and method for DC offset compensation. An amplifier receives an input signal (AIN) and provides an amplified output signal (SOUT) and a feedback path provides DC offset compensation. The feedback path comprises at least one voltage controlled oscillator (VCO) and a counter. The VCO provides, over time, a first VCO output signal based on said amplified output signal and a second VCO output signal based on a reference signal (VREF). The counter generates first pulse counts based upon the first VCO output signal and second pulse counts based upon the second VCO output signal and provides a compensation signal based on a comparison of the first and second pulse counts. One voltage controlled oscillator may sequentially receive a signal based on said amplifier output signal and the reference signal from a multiplexer so as to sequentially produce the first and second VCO output signals.

Abstract: An autobias vehicular microphone system (300) includes a microphone (301) which uses an amplifier (306) for amplifying an output of the microphone. A first feedback path (308) provides an amplifier output signal to the amplifier input for providing amplifier linearity, and a second feedback path (305) is used for providing bias to a voltage reference (303). The voltage reference (303) operates to provide an autobias to the amplifier (306) based upon amplifier load-ing. By holding the bias point to a constant voltage, a constant clip level can be maintained depending on varying load conditions of electronic devices (307, 309, 311) using the microphone (301). Additionally, one or more switches can be used to vary the bias point which can be interpreted to control functionality of the electronic devices (307, 309, 311).

Abstract: A signal amplifying circuit and associated methods and apparatuses, the circuit comprising: a signal path extending from an input terminal to an output terminal, a gain controller arranged to control the gain applied along the signal path in response to a control signal; an output stage within the signal path for generating the output signal, the output stage having a gain that is substantially independent of its supply voltage, and a variable voltage power supply comprising a charge pump for providing positive and negative output voltages, the charge pump comprising a network of switches that is operable in a number of different states and a controller for operating the switches in a sequence of the states so as to generate positive and negative output voltages together spanning a voltage approximately equal to the input voltage.

Abstract: System and method for amplifying an input signal to generate an output signal. The system includes a current generator, an oscillator, and a comparator. The current generator is configured to receive a first voltage signal, and generate a first current signal based on at least information associated with the first voltage signal and the first reference signal. The oscillator is configured to receive at least the first current signal and a second reference signal, and to generate a second voltage signal based on at least information associated with the first current signal and the second reference signal, the second voltage signal being associated with a modulation frequency. Additionally, the comparator is configured to receive the second voltage signal and a third voltage signal, and to generate a modulation signal related to the modulation frequency based on at least information associated with the second voltage signal and the third voltage signal.

Abstract: An amplification apparatus comprises: an amplifier circuit that amplifies an input audio signal and outputs an output audio signal; a first signal level determining unit that determines whether or not a signal level of the output audio signal outputted from the amplifier circuit is lower than a silence determination reference value; and a power-supply control unit that shifts the amplification apparatus from a power-on state to a power-off state, when it is determined that the signal level of the output audio signal outputted from the amplifier circuit is lower than the silence determination reference value.

Abstract: An apparatus is provided for remotely monitoring a plurality of amplifiers on a display device. The amplifiers are provided to process audio signals and directly or indirectly connected to a network. In the apparatus, a collecting section collects a group code from each of the amplifiers through the network. The group code is allocated to each amplifier according to a grouping system for grouping the plurality of the amplifiers. A display control section displays a tree diagram of the amplifiers according to the collected group codes on the display device as a graphical representation of the grouping system.

Abstract: A device is used for compensating a supply voltage from a power supply, the supply voltage powers an audio device. The device includes a detecting circuit and a storing circuit. The detecting circuit is used for detecting an audio signal from the audio device, generating a first level signal when detecting that the audio signal has a first characteristic, and generating a second level signal when detecting that the audio signal has a second characteristic. The storing circuit is used for storing energy according to the first level signal, and releasing energy to increase the supply voltage according to the second level signal. A related method and electronic apparatus are also provided.

Abstract: An offset correction circuit removes DC offset from an analog audio output signal by comparing transitions of digital audio values to which the analog output signal is related to the output of a monitor that monitors the analog output signal. The monitor may be a zero-crossing detector and the transitions of the digital signal that are compared may be transitions of the most-significant bit (MSB) of the digital audio values. A filtering algorithm or filter circuit may be used to average a result of the comparison of the transitions, so that the offset is slowly and accurately removed. A chopped or autozero comparator may be used to further reduce error in the offset determination.

Abstract: An audio amplifier receiving a digital input audio signal and generating an output audio signal for driving a speaker includes a digital input class D amplifier configured to receive the digital input audio signal and to generate the output audio signal. The digital input class D amplifier includes a first modulator configured to receive the digital input audio signal and to generate a quasi-digital signal in n-bit, and a class D modulator configured to receive the n-bit quasi-digital signal and to generate the output audio signal, the class D modulator implementing an analog feedback loop. In some embodiments, the class D modulator is implemented using a PWM modulator. In other embodiments, the PWM modulator incorporates enhanced features to improve the output noise characteristics.

Abstract: An image display apparatus includes: an image information input section; an image display section for displaying an image corresponding to the image information; a first sound input section adapted to input a first sound signal; a first sound amplification section adapted to amplify the first sound signal to generate a first amplified sound signal; a second sound input section adapted to input a second sound signal; a second sound amplification section adapted to amplify the second sound signal to generate a second amplified sound signal; a sound mixing section adapted to mix the first amplified sound signal and the second amplified sound signal with each other; an audio output section adapted to output an audio corresponding to a sound signal input from the sound mixing section; and an operation mode setting section adapted to set an operation mode, wherein the sound mixing section mixes the first amplified sound signal and the second amplified sound signal based on the operation mode set by the operation mo

Abstract: The invention concerns in a first aspect an audio system comprising a microphone, audio signal processing means, an output transducer and means for detecting a possible feedback tone and the corresponding frequency of the feedback tone in the audio system between the output transducer and the microphone. According to the invention means for counteracting feedback are provided. Further, means are provided for changing the phase of the audio signal at a given frequency. In a further aspect, a binaural hearing aid system comprising first and second hearing instruments according to the first aspect, each hearing instrument comprising transceiver circuitry allowing an exchange of signals between the two hearing instruments, and wherein the binaural hearing aid system is adapted to provide that a phase change introduced in the first audio signal by a controller of the first hearing instrument is or can be introduced in the second audio signal of the second hearing instrument via said transceiver circuitry.

Abstract: An amplifying circuit capable of suppressing spikes of an audio signal includes an integration module, a comparison module, an output module, a feedback module, and a limiting module. The integration module is used for receiving an input signal and generating a first voltage signal corresponding to the input signal. The comparison module is coupled to the integration module for receiving the first voltage signal and a reference signal, and generating a comparison signal. The output module is coupled to the comparison module for generating an audio signal according to the comparison signal. The feedback module is coupled between the output module and the integration module for feeding back an output signal to the integration module. The limiting module is coupled between the feedback module and the integration module for limiting the comparison signal to be within a predetermined range.

Abstract: A device and methods are provided for a guitar amplifier. In one embodiment, an amplifier includes an overdrive shaping circuit including one or more elements for harmonic shaping of a received signal. The amplifier may also include a power amplifier circuit configured to receive the harmonic shaped signal from the overdrive shaping circuit, wherein the power amplifier circuit includes a switchmode amplifier to amplify the harmonic shaped signal includes one or more elements to increase the output impedance of the switchmode amplifier. An output of the amplifier can output a signal with desired harmonic shaping and a dynamic response.

Abstract: Disclosed is an audio amplification circuit comprising: an input terminal for receipt of an audio input signal; a first preamplifier having an input operatively coupled to the input terminal and operable to provide a first amplified audio signal with a first signal amplification; a second preamplifier having an input operatively coupled to the input terminal and operable to provide a second amplified audio signal with a second signal amplification, smaller than the first signal amplification; a switch having a first input operatively coupled to the first preamplifier, a second input operatively coupled to the second preamplifier, and an output; an analogue-to-digital converter operatively coupled to the output of the switch and operable to provide a digital audio signal; a signal selection circuit operable to control the switch to selectively provide one of the first and second amplified audio signals on the output of the switch.

Abstract: An amplifier includes: a first operational signal path arranged to generate a first pre-output signal according to an input signal under a first operating mode of the amplifier; a second operational signal path arranged to generate a second pre-output signal according to the input signal under a second operating mode of the amplifier; and an output stage, coupled to the first operational signal path and the second operational signal path, for outputting a first output signal according to the first pre-output signal under the first operating mode and outputting a second output signal according to the second pre-output signal under the second operating mode, wherein the first operational signal path and the second operational signal path are arranged to share at least one common circuit element for generating the first pre-output signal and the second pre-output signal under the first operating mode and the second operating mode, respectively.

Abstract: [Problem] The purpose is to provide an amplifier capable of reducing the quantization error caused by conversion accuracy in an A/D converter circuit and, particularly, capable of improving the S/N ratio and distortion rate when an input audio signal is small. [Solution] In an amplifier (1) using a voltage variable power supply (73) as a power supply to follow an input audio signal level (S1) to the amplifier (1) in order to increase or decrease the level of supply voltage supplied to a power amplifier stage (4), when the level of source power of the power amplifier stage (4) is changed, the voltage level of a reference voltage supplied to an A/D converter (62) of a negative feedback circuit is controlled.

Abstract: The invention relates to a hearing aid with at least one sound receiver and a sound generator. The hearing aid has an audio signal unit operatively connected to the sound generator, the audio signal unit being designed to generate an audio signal perceptible to a human ear. The audio signal has a plurality of mutually different frequencies of a frequency range. The audio signal unit has at least one tone generator. The at least one tone generator is designed to generate the audio signal with at least one fundamental frequency representing a tone and with harmonics of the fundamental frequency.

Abstract: An audio amplifier is operated in an audio system with optimized source impedance to minimize distortion in a loudspeaker that is paired with the audio amplifier. The audio amplifier provides an amplified audio signal to drive the loudspeaker. A variable output impedance of the audio amplifier is controlled using a feedback control loop to allow negative output impedance at low frequencies that changes to positive output impedance at higher frequencies. The change from negative output impedance to positive output impedance occurs at a determined threshold frequency or determined transitional frequency band.

Abstract: An apparatus for providing an audio signal to drive a speaker system includes first and second audio channels. The first audio channel has a first class-D amplifier for receiving an input signal, and a first reconstruction filter for receiving an output from the first class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The second audio channel has a second class-D amplifier for receiving an input audio signal, and a second reconstruction filter for receiving an output from the second class-D amplifier and reconstructing therefrom an output audio signal for driving the speaker system. The first and second reconstruction filters have corresponding first and second planar inductors, with the second planer inductor being magnetically coupled to the first planar inductor.

Abstract: An audio playing device for an electronic device includes an amplifier circuit, a voltage divider circuit, and a speaker. A south bridge of the electronic device is electrically connected to the amplifier circuit via the voltage divider circuit, and a sound card of the electronic device is electrically connected to the amplifier circuit. The south bridge generates electronic signals corresponding to startup prompt tones of the electronic device, and the electronic signals corresponding to startup prompt tones of the electronic device are transmitted to the speaker via the voltage divider circuit and the amplifier circuit to play. The sound card processes audio files, and electronic signals corresponding to the processed audio files are transmitted to the speaker via the amplifier circuit to play.

Abstract: A low-noise pre-amplifier with an active load element is integrated into a microphone. The microphone has an acoustic sensor coupled to the intrinsic pre-amplifier. A controllable current source is coupled to the intrinsic pre-amplifier and supplies a pre-amplifier bias current. A current source controller is coupled to the current source and controls the amplitude of the pre-amplifier bias current to maintain the intrinsic pre-amplifier at a bias point at which the intrinsic pre-amplifier amplifies microphone signals produced by the acoustic sensor. The intrinsic pre-amplifier may be actively regulated at the pre-determined bias point using negative feedback. Alternatively, the intrinsic pre-amplifier may be set to the pre-determined bias point by sweeping the pre-amplifier bias current for the intrinsic pre-amplifier over a range of currents.

Abstract: Direct current (DC) offset in and audio driver can cause a constant drain on power even when there is no sound. Furthermore it can cause an audible pop when the audio driver is enabled. A scaled replica output stage can be employed to perform DC offset cancellation offline during a sampling phase. Once DC offset cancellation is achieved, the audio driver uses a full scale output stage during the operation phase.

Abstract: A driver circuit includes a first driver amplifier that is configured to generate a first output in response to a first reference voltage input and a first audio input; a second driver amplifier that is configured to generate a second output in response to the first reference voltage and a second audio input; and a common mode (CM) amplifier, coupled to the first driver amplifier and the second driver amplifier. The CM amplifier is configured to generate an output in response to a second reference voltage input, the first reference voltage input being a divided version of the output. Gains of the first driver amplifier, second driver amplifier and the CM amplifier are equal. Noise at the output appears across a plurality of resistors coupled at the outputs of the first driver amplifier, second driver amplifier and the CM amplifier and cancels with respect to the output of the CM amplifier.

Abstract: Various embodiments of the present invention are directed to methods and systems that reduce acoustic echoes in audio signals in accordance with changing conditions at first and second locations that are linked together in a communication system. In particular, one embodiment of the present invention relates to a method for determining an approximate impulse-response vector for canceling an acoustic echo resulting from an audio signal transmitted from the first location to the second location. This method includes forming a trust region within a search space based on computing a recursive specification vector defining the trust region. The method also includes computing a recursive shadow-impulse-response vector that lies substantially within the trust region, and computing the approximate impulse-response vector based on the recursive shadow-impulse-response vector and the recursive specification vector.

Abstract: An apparatus for driving speakers includes user-configurable amplifier cells for driving selected speakers, a synchronous rectifier circuit, and a control system. Each cell connects between power rails. The rectifier circuit provides current on the rails for consumption by the cells. The current depends on the configuration. The control system implements a model of the rectifier circuit and cells and uses it to control an audio input signal in response to information concerning electrical outputs of the amplifier cells. This indirectly limits current drawn from the synchronous rectifier circuit.

Abstract: An energy-efficient consumer device audio power output stage provides improved battery life and reduced power dissipation. A power supply having a selectable operating mode supplies the power supply rails to the power amplified output stage. The operating mode is controlled in conformity with the audio signal level, which may be determined from a volume control setting of the device and/or from a signal level detector that determines the amplitude of the signal being amplified. The power supply may be a charge pump in which the operating mode uses a capacitive divider to provide for selection of a power supply output voltage that is a rational fraction of the power supply output voltage in a full-voltage operating mode.

Abstract: Provided is a read-out circuit that is connected to a microphone and configured to linearly amplify a current signal generated by the microphone and output the amplified current signal. The read-out circuit includes an amplification unit and a feedback resistor. The amplification unit has an amplification gain between 0 and 1. The feedback resistor is connected between input and output terminals of the amplification unit. As the amplification gain of the amplification unit becomes closer to 1, an input impedance becomes higher. A preamp of the read-out circuit can have a high input impedance due to the amplification gain, and the read-out circuit can be manufactured using a CMOS process.

Abstract: A circuit for diminishing mismatch effects between at least two switched signals includes at least three processing circuits configured to receive at least two switched signals such that each of the switched signals is associated with one of the processing circuits leaving at least one unassociated processing circuit. A controller circuit is configured to switch one of the switched signals to be associated with one of the unassociated processing circuit(s) upon at least one specified interval such as, for example, at a transition of the switched signal. The circuit may be incorporated into an audio amplifier configured to provide information carried on the switched signals to one or more speakers that provide an audio output. A one-processor circuit approach includes switching frames of a switched signal between positive and negative inputs of a processor circuit to average out errors introduced by the processor circuit.

Abstract: An apparatus for outputting audio signals. The apparatus for outputting audio signals includes a pulse density modulation (PDM) unit for PDM modulating an input audio signal to output a modulated audio signal, a driving signal generator for generating at least one driving signal to control switching amplification operations based on the modulated audio signal, and a power switching amplifier having at least one switch that is turned on or turned off in response to the driving signal and performs the switching amplification operations for using the at least one switch to output an amplified audio signal that corresponds to the modulated audio signal, wherein the at least one switch includes at least one from among a gallium nitride (GaN) transistor, gallium arsenide (GaAs) transistor, and a silicon carbide (SiC) transistor.

Abstract: An audio power amplifier with a four-quadrant power supply having a synchronous output rectifier that includes a planar transformer. The amplifier includes a first amplification unit including a switching voltage amplifier with a command signal input and an amplified signal output. Control electronics provide a signal input to the first amplification unit.

Abstract: A capacitive sensor amplifier circuit comprising: a capacitive sensor; a bias voltage supply connected across the capacitive sensor via a bias resistor; an operational amplifier having an input connected to the capacitive sensor; and a feedback capacitor connected between the input and an output of the amplifier, the input and output being of the same sign.