A class D amplifier receives and amplifies a differential analog signal which is then differentially integrated. Two pulse width modulators generate pulse signals corresponding to the differentially integrated analog signal and two power units generate output pulse signals. The outputs the power units are coupled to input terminals of integrators via a resistor feedback network. An analog output unit converts the pulse signals to an output analog signal. The differential integration circuitry implements a soft transition between mute/un-mute. In mute, the integrator output is fixed. During the soft transition, the PWM outputs change slowly from a fixed 50% duty cycle to a final value to ensure that no pop noise is present in the output as a result of mode change.

A receiver and a program capable of, when they have received a pulse noise together with a reception signal, improving quality of the reception signal are provided. A receiver according to the present disclosure includes a received-signal amplification circuit configured to amplify a monitoring received signal branched from a received signal, a gain control circuit configured to set a gain setting value for an AGC operation in the received-signal amplification circuit, the AGC operation being an operation for making an amplitude of an amplified monitoring received signal fall within a predetermined range, a pulse detection circuit configured to monitor a change in the gain setting value and detect whether or not a pulse noise is contained in the received signal based on whether or not the change in the gain setting value meets a predetermined condition.

A noise suppression apparatus disclosed is capable of suppressing pulse noise in an input signal even in a situation in which the level of the input signal changes. The pulse noise mixed in the input signal is suppressed, and linear prediction coefficients for the input signal is derived by linear prediction analysis. A prediction residual signal is then calculated from the input signal using the linear prediction coefficient. A threshold value is calculated based on the signal level of the input signal and the signal level of the prediction residual signal is compared with the threshold value. A limit control is performed on the prediction residual signal depending on a result of the comparison, and an output signal is generated based on the prediction residual signal having been subjected to the limit control using the linear prediction coefficient.

An interference sensor device is disclosed. The interference sensor device includes a first conductive plate, a second conductive plate aligned parallel to the first conductive plate, a non-conductive matter between the first conductive plate and the second conductive plate and a coil electrically coupled to the first conductive plate and the second conductive plate.

A class D amplifier receives and amplifies a differential analog signal which is then differentially integrated. Two pulse width modulators generate pulse signals corresponding to the differentially integrated analog signal and two power units generate output pulse signals. The outputs the power units are coupled to input terminals of integrators via a resistor feedback network. An analog output unit converts the pulse signals to an output analog signal. The differential integration circuitry implements a soft transition between mute/un-mute. In mute, the integrator output is fixed. During the soft transition, the PWM outputs change slowly from a fixed 50% duty cycle to a final value to ensure that no pop noise is present in the output as a result of mode change.

The present exemplary embodiments provide an audio signal muting apparatus and a digital signal conversion apparatus which remove a negative pop noise in a predetermined large range using a negative power for the transistor of the audio signal muting apparatus.

The present disclosure discloses an audio output circuit including an audio power amplifier, a mute control circuit and a microcontroller, the audio power amplifier includes a power input terminal, a mute control terminal and an audio signal output terminal, the power input terminal is used to connect a power supply to obtain a power supply voltage, the mute control terminal is connected with the microcontroller through the mute control circuit and is grounded by a pull-down resistor, the audio signal output terminal is used to output an audio signal, the mute control circuit is also connected to the power supply for disconnecting the mute control terminal from the microcontroller when the power supply voltage is less than a preset voltage. The present disclosure also provides an audio device. According to the present disclosure, it is possible to effectively prevent the POP sound of the speaker of the audio device.

A class D amplifier receives and amplifies a differential analog signal which is then differentially integrated. Two pulse width modulators generate pulse signals corresponding to the differentially integrated analog signal and two power units generate output pulse signals. The outputs the power units are coupled to input terminals of integrators via a resistor feedback network. An analog output unit converts the pulse signals to an output analog signal. The differential integration circuitry implements a soft transition between mute/un-mute. In mute, the integrator output is fixed. During the soft transition, the PWM outputs change slowly from a fixed 50% duty cycle to a final value to ensure that no pop noise is present in the output as a result of mode change.

A noise suppression apparatus disclosed is capable of suppressing pulse noise in an input signal even in a situation in which the level of the input signal changes. The pulse noise mixed in the input signal is suppressed, and linear prediction coefficients for the input signal is derived by linear prediction analysis. A prediction residual signal is then calculated from the input signal using the linear prediction coefficient. A threshold value is calculated based on the signal level of the input signal and the signal level of the prediction residual signal is compared with the threshold value. A limit control is performed on the prediction residual signal depending on a result of the comparison, and an output signal is generated based on the prediction residual signal having been subjected to the limit control using the linear prediction coefficient.

The present disclosure discloses an audio output circuit including an audio power amplifier, a mute control circuit and a microcontroller, the audio power amplifier includes a power input terminal, a mute control terminal and an audio signal output terminal, the power input terminal is used to connect a power supply to obtain a power supply voltage, the mute control terminal is connected with the microcontroller through the mute control circuit and is grounded by a pull-down resistor, the audio signal output terminal is used to output an audio signal, the mute control circuit is also connected to the power supply for disconnecting the mute control terminal from the microcontroller when the power supply voltage is less than a preset voltage. The present disclosure also provides an audio device. According to the present disclosure, it is possible to effectively prevent the POP sound of the speaker of the audio device.