This application relates to an active current compensation device which actively compensates for a noise occurring in a common mode in each of two or more high-current paths. In one aspect, the active current compensation device includes a sensing unit configured to generate an output signal corresponding to a common-mode noise current on each of the two or more high-current paths, and an amplification unit configured to amplify the output signal to generate an amplified current. The device may also include a compensation unit configured to generate a compensation current on the basis of the amplified current and allow the compensation current to flow to each of the two or more high-current paths, and a malfunction detection unit configured to detect a malfunction of the amplification unit. The malfunction detection unit and at least a portion of the amplification unit may be embedded in one integrated circuit (IC) chip.

An improved audio amplifier system can both reduce power consumption by supporting a standby mode and shorten wake time when resuming from the standby mode. The audio amplifier system may reduce power by entering a sleep or standby state in response to a command and/or detecting that an audio input signal is not received. Further, the audio amplifier system may use a burst generator to periodically or intermittently activate the power supply during standby mode. By periodically or intermittently activating the power supply, one or more of the capacitors may be charged. By charging the capacitors during standby mode, the time to wake from standby mode may be significantly reduced. In some cases, the wake time may be reduced by several order of magnitudes (e.g., from seconds to milliseconds).

An output driver for an audio system includes a pre-charge circuit. The pre-charge circuit includes a charging amplifier and a feedback bias circuit. A charging amplifier includes an output node for coupling to a capacitive load, a first input node for receiving a reference voltage, a second input node for coupling to the output node of the charging amplifier, and a bias node for receiving a bias current. An output current of the charging amplifier varies with the bias current. The feedback bias circuit is coupled to the output node to sense an output voltage of the charging amplifier, and configured to provide the bias current that varies with the output voltage of the charging amplifier.

A power management integrated circuit (PMIC) can improve the ramp up speed of a boost converter with the inclusion of a controllable switch that may modify the connection of an output capacitor to reduce the ramp time as the output voltage is ramping to a desired boost setpoint. The switch may be controlled using jump start logic to switch a first plate or terminal of the output capacitor from a ground connection to a voltage supply connection. Once a threshold voltage is reached, the first plate of the capacitor may be switched from the supply voltage to ground. The PMIC may further include a quick start assembly that can drive the boost converter at a high duty-cycle.

Disclosed are a signal processing device and an image display apparatus including the same. The signal processing device includes an amplifier to perform amplification based on an input differential signal, an output driver to output an audio output signal based on an output signal from the amplifier, a reference voltage output device to output a reference voltage in response to power ON, a pre-output driver configured to pre-compensate for an offset voltage and output a compensation signal, based on an output signal from the amplifier after the power ON, and a first switching device disposed between an output terminal of the output driver and an output terminal of the pre-output driver, wherein the output driver operates after the first switching device is turned on in response to the power ON. Accordingly, pop noise and harmonic distortion in case in which power is turned on may be reduced.

A power management integrated circuit (PMIC) can improve the ramp up speed of a boost converter with the inclusion of a controllable switch that may modify the connection of an output capacitor to reduce the ramp time as the output voltage is ramping to a desired boost setpoint. The switch may be controlled using jump start logic to switch a first plate or terminal of the output capacitor from a ground connection to a voltage supply connection. Once a threshold voltage is reached, the first plate of the capacitor may be switched from the supply voltage to ground. In certain cases, by switching the connection of the output capacitor between ground and a supply voltage based on one or more threshold voltages or a boost setpoint, the time to ramp from an initial voltage to a desired boost setpoint may be reduced.

An amplifier-embedded video surveillance IP speaker system is disclosed. The present disclosure includes an IP video device, an IP audio device, and a sensor, wherein audio data of a monitor agent using a remote user terminal is transmitted to an amplifier-embedded IP speaker having an assigned IP address to then be output, or wherein a remote control command is transmitted to an amplifier-embedded IP speaker, thereby outputting a warning sound.

A method for eliminating unstable noise is provided and applicable to a sound recording device and implemented by a codec. The method includes: activating the sound recording device to start recording; setting a suppression duration and a cutoff frequency switching duration according to unstable noise and a DC offset value of the sound recording device; processing a front-end audio of a recorded sound by a filter having a first cutoff frequency to make the unstable noise in the front-end audio quickly converge, and outputting a filtered audio signal; suppressing the filtered audio signal according to the suppression duration to eliminate the unstable noise; and adjusting the first cutoff frequency of the filter to a second cutoff frequency according to the cutoff frequency switching duration, where the first cutoff frequency is greater than the second cutoff frequency. A device for eliminating unstable noise is also provided.

A class-D amplifier with low pop-click noise is shown. A loop filter, a control signal generator, a first power driver, and a first feedback circuit are provided within the class-D amplifier to establish a first loop for signal amplification. The class-D amplifier further has a settling circuit and a pre-charging circuit. The settling circuit is configured to be combined with the loop filer and the control signal generator to establish a second loop to settle the loop filter and the control signal generator before the first loop is enabled. The pre-charging circuit is configured to pre-charge a positive output terminal and a negative output terminal of the first power driver.

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.