Abstract: An amplifier system includes an output circuit, a processor circuit, a feedback circuit, and a controller circuit. The output circuit outputs an output signal and returns a digital output feedback signal. The processor circuit receives a filtered error audio signal and outputs a pulse width modulation control signal to the output circuit. An addition unit of the feedback circuit adds the negative value of the digital output feedback signal to the digital input signal to obtain the error audio signal. A variable filter unit of the feedback circuit filters the error audio signal and outputs the filtered error audio signal. A compensation unit of the variable filter unit changes the gain characteristics of the variable filter unit. The controller circuit adjusts one or more parameters of the compensation unit according to a pre-compensation signal so as to change the gain characteristics of the variable filter unit.

Abstract: A circuit includes a signal modification circuit, a power stage circuit, and a boost converter circuit. The signal modification circuit generates a modified signal according to an input signal. The power stage circuit is electrically coupled to the signal modification circuit and receives a first voltage to amplify the modified signal and generate an output signal. The boost converter circuit selectively controls the amplitude of the first voltage. The signal modification circuit electrically coupled to the boost converter circuit. Therefore, the signal modification circuit is configured to dynamically adjust its own gain corresponding to the value of the first voltage, and the input signal is modified into the modified signal based on the gain of the signal modification circuit.

Abstract: The present invention provides a receiving circuit, wherein the receiving circuit includes a first ADC, an attenuator, a second ADC, a harmonic generation circuit and an output circuit. In the operations of the receiving circuit, the first ADC performs an analog-to-digital operation on an analog input signal to generate a first digital output signal, the attenuator reduces strength of the analog input signal to generate an attenuated analog input signal, the second ADC performs the analog-to-digital operation on the attenuated analog input signal to generate a second digital input signal, the harmonic generation circuit generates at least one harmonic signal according to the second digital input signal, and the output circuit deletes a harmonic component of the first digital input signal by using the at least one harmonic signal to generate an output signal.

Abstract: The present invention provides a feedback system including a mixing circuit, a forward circuit, a feedback circuit, a feedback gain circuit and a control circuit. In the operations of the feedback system, the mixing circuit generates a mixed signal according to an input signal and a feedback signal, the forward circuit processes the mixed signal to generate an output signal, the feedback gain circuit and the feedback circuit generates the feedback signal according to the output signal, and the control circuit determines a feedback gain of the feedback gain circuit according to a gain of the forward circuit.

Abstract: An audio device is adapted to receive and process a digital audio signal and output an analog audio signal. The audio device includes an adder, a digital-to-analog conversion circuit, an amplifying circuit, a voltage detecting circuit and an offset compensating circuit. The voltage detecting circuit detects a supply voltage received by the amplifying circuit. The offset compensating circuit generates a DC offset compensation value according to the supply voltage. The adder adds the digital audio signal and the DC offset compensation value to output an added signal. The digital-to-analog conversion circuit converts the added signal into a converted analog audio signal. The amplifying circuit amplifies the converted analog signal to output an amplified analog signal. Accordingly, the audio device can reduce pop noise caused by a DC offset.

Abstract: A temperature computing parameter providing circuit, configured to generate sensing voltage values and calibrated voltage values as temperature computing parameters for a target electronic device, including: a parameter computing circuit, configured to compute a reference voltage, which is a cross voltage of a reference resistor coupled to the target electronic device in series, to generate a reference voltage value, and to compute the sensing voltage, which is a cross voltage of the target electronic device, to generate the sensing voltage value; a reference temperature sensing circuit, configured to sense a current reference temperature of the reference resistor; and a computing circuit, configured to calibrate the reference voltage value to generate the calibrated voltage value according to a calibrating function and the current reference temperature. The calibrating function corresponds to a resistance-temperature variation function.

Abstract: An audio device for reducing pop noise is adapted to compensate for a direct current (DC) offset of an audio source signal and output the audio source signal to an audio playing device. The audio device includes a linear operation circuit, an adder, a digital-to-analog circuit, and an amplification circuit. The digital-to-analog circuit is coupled between the adder and the amplification circuit. The linear operation circuit generates a DC offset value based on a linear equation, a temperature parameter, a slope parameter, and a constant. The adder is configured to process an input signal and the DC offset value to generate a calibration signal. The digital-to-analog circuit is configured to convert a calibration signal in a digital form to a calibration signal in an analog form. The amplification circuit is configured to process the calibration signal in the analog form to output the audio source signal.

Abstract: The present invention provides a receiving circuit, wherein the receiving circuit includes a first ADC, an attenuator, a second ADC, a harmonic generation circuit and an output circuit. In the operations of the receiving circuit, the first ADC performs an analog-to-digital operation on an analog input signal to generate a first digital output signal, the attenuator reduces strength of the analog input signal to generate an attenuated analog input signal, the second ADC performs the analog-to-digital operation on the attenuated analog input signal to generate a second digital input signal, the harmonic generation circuit generates at least one harmonic signal according to the second digital input signal, and the output circuit deletes a harmonic component of the first digital input signal by using the at least one harmonic signal to generate an output signal.

Abstract: The present invention provides a feedback system including a mixing circuit, a forward circuit, a feedback circuit, a feedback gain circuit and a control circuit. In the operations of the feedback system, the mixing circuit generates a mixed signal according to an input signal and a feedback signal, the forward circuit processes the mixed signal to generate an output signal, the feedback gain circuit and the feedback circuit generates the feedback signal according to the output signal, and the control circuit determines a feedback gain of the feedback gain circuit according to a gain of the forward circuit.

Abstract: An audio device is adapted to receive and process a digital audio signal and output an analog audio signal. The audio device includes an adder, a digital-to-analog conversion circuit, an amplifying circuit, a voltage detecting circuit and an offset compensating circuit. The voltage detecting circuit detects a supply voltage received by the amplifying circuit. The offset compensating circuit generates a DC offset compensation value according to the supply voltage. The adder adds the digital audio signal and the DC offset compensation value to output an added signal. The digital-to-analog conversion circuit converts the added signal into a converted analog audio signal. The amplifying circuit amplifies the converted analog signal to output an amplified analog signal. Accordingly, the audio device can reduce pop noise caused by a DC offset.

Abstract: Disclosed is a harmonic compensation device capable of effectively reducing the harmonic distortion of an analog output signal. The harmonic compensation device includes a harmonic compensator, a mixer, a digital-to-analog converter, and an analog output circuit. The harmonic compensator is configured to generate a digital compensation signal according to a digital input signal, in which the digital compensation signal includes the harmonic components of the digital input signal. The mixer is configured to generate a digital output signal according to the digital input signal and the digital compensation signal. The digital-to-analog converter is configured to generate an analog input signal according to the digital output signal. The analog output circuit is configured to generate an analog output signal according to the analog input signal.

Abstract: An audio device for reducing pop noise is adapted to compensate for a direct current (DC) offset of an audio source signal and output the audio source signal to an audio playing device. The audio device includes a linear operation circuit, an adder, a digital-to-analog circuit, and an amplification circuit. The digital-to-analog circuit is coupled between the adder and the amplification circuit. The linear operation circuit generates a DC offset value based on a linear equation, a temperature parameter, a slope parameter, and a constant. The adder is configured to process an input signal and the DC offset value to generate a calibration signal. The digital-to-analog circuit is configured to convert a calibration signal in a digital form to a calibration signal in an analog form. The amplification circuit is configured to process the calibration signal in the analog form to output the audio source signal.

Abstract: A temperature computing parameter providing circuit, configured to generate sensing voltage values and calibrated voltage values as temperature computing parameters for a target electronic device, including: a parameter computing circuit, configured to compute a reference voltage, which is a cross voltage of a reference resistor coupled to the target electronic device in series, to generate a reference voltage value, and to compute the sensing voltage, which is a cross voltage of the target electronic device, to generate the sensing voltage value; a reference temperature sensing circuit, configured to sense a current reference temperature of the reference resistor; and a computing circuit, configured to calibrate the reference voltage value to generate the calibrated voltage value according to a calibrating function and the current reference temperature. The calibrating function corresponds to a resistance-temperature variation function.

Abstract: Disclosed is a harmonic compensation device capable of effectively reducing the harmonic distortion of an analog output signal. The harmonic compensation device includes a harmonic compensator, a mixer, a digital-to-analog converter, and an analog output circuit. The harmonic compensator is configured to generate a digital compensation signal according to a digital input signal, in which the digital compensation signal includes the harmonic components of the digital input signal. The mixer is configured to generate a digital output signal according to the digital input signal and the digital compensation signal. The digital-to-analog converter is configured to generate an analog input signal according to the digital output signal. The analog output circuit is configured to generate an analog output signal according to the analog input signal.

Abstract: An audio device includes a digital-to-analog converter, an amplifier, a speaker, a power management unit and a temperature sensor. The digital-to-analog converter is configured to convert a digital audio signal into an analog audio signal. The amplifier is coupled to the digital-to-analog converter and configured to amplify the analog audio signal and generate an amplified analog audio signal. The speaker is coupled to the amplifier and configured to broadcast the amplified analog audio signal. The power management unit is configured to provide the amplifier with a first working voltage and provide the digital-to-analog converter with a second working voltage. The temperature sensor is coupled to the speaker and configured to generate a temperature detection signal according to a temperature of the speaker. Wherein, the power management unit adjusts at least one of the first working voltage and the second working voltage according to the temperature detection signal.

Abstract: A digital microphone system, audio control device and control method thereof is related to the method for controlling a digital microphone circuit including receiving a clock signal; detecting that the clock signal is maintained at a predetermined level for a duration; when the duration reaches a given time, switching a transmission type of a data pin; in a data mode, outputting a digital audio signal to a data line via the data pin in an output type; and in a command mode, receiving a command signal from the data line via the data pin in an input type.

Abstract: The present invention provides a signal processing circuit and a signal processing method applied to a headset. In the present invention, the signal processing circuit adjusts gain and phase of a left channel signal and a right channel signal to generate a first adjust signal, and a recorded sound from a microphone is added by the first adjust signal to cancel a coupled signal. In addition, the signal processing circuit adjusts gain and phase of the right channel signal to generate a second adjust signal, and the right channel signal is added by the second adjust signal to cancel a coupled signal; and the signal processing circuit adjusts gain and phase of the left channel signal to generate a third adjust signal, and the left channel signal is added by the third adjust signal to cancel a coupled signal.

Abstract: A digital-to-analog converting (DAC) circuit is utilized for converting a 1-bit stream into an analog output signal. The DAC includes an N-bit encoder, a multiplexer, a low-pass filter, and a digital-to-analog conversion circuit. The N-bit encoder is utilized for receiving the 1-bit stream and encoding the 1-bit stream to generate an N-bit stream, where N is larger than 1; the multiplexer is utilized for selectively outputting the N-bit stream or a zero signal as an output signal according to a selection signal; the low-pass filter is utilized to generate a filtered output signal according to the output signal; and the digital to analog conversion circuit is utilized to generate the analog output signal according to the filtered output signal.

Abstract: A signal processing apparatus for generating a noise cancellation signal in accordance with a noise signal includes an inverting circuit and a selecting circuit. The inverting circuit is employed for inverting a first signal to generate an inverted first signal. The selecting circuit is coupled to the inverting circuit, and employed for selecting one of the first signal and the inverted first signal as an output signal.

Abstract: An audio device includes a digital-to-analog converter, an amplifier, a speaker, a power management unit and a temperature sensor. The digital-to-analog converter is configured to convert a digital audio signal into an analog audio signal. The amplifier is coupled to the digital-to-analog converter and configured to amplify the analog audio signal and generate an amplified analog audio signal. The speaker is coupled to the amplifier and configured to broadcast the amplified analog audio signal. The power management unit is configured to provide the amplifier with a first working voltage and provide the digital-to-analog converter with a second working voltage. The temperature sensor is coupled to the speaker and configured to generate a temperature detection signal according to a temperature of the speaker. Wherein, the power management unit adjusts at least one of the first working voltage and the second working voltage according to the temperature detection signal.