The present disclosure relates in a first aspect to a method of detecting leakage current from a DC bias voltage circuit of an integrated circuit for a capacitive microelectro mechanical systems (MEMS) transducer. A test signal with a predetermined frequency and level is superimposed on a first DC bias voltage generated by the DC bias voltage circuit.

The present disclosure relates in a first aspect to a method of detecting leakage current from a DC bias voltage circuit of an integrated circuit for a capacitive microelectro mechanical systems (MEMS) transducer. A test signal with a predetermined frequency and level is superimposed on a first DC bias voltage generated by the DC bias voltage circuit.

The present invention provides an offset calibration circuit used in a signal processing circuit, wherein the offset calibration circuit includes a supply voltage detection circuit and a calibration circuit. The supply voltage detection circuit is configured to detect a level of a supply voltage to generate a detection result, wherein the supply voltage is provided to an output stage in the signal processing circuit. The calibration circuit is configured to calculate a digital compensation value according to the detection result, wherein the digital compensation value is used for a digital processing circuit in the signal processing circuit to perform a DC offset calibration.

The present invention provides an offset calibration circuit used in a signal processing circuit, wherein the offset calibration circuit includes a supply voltage detection circuit and a calibration circuit. The supply voltage detection circuit is configured to detect a level of a supply voltage to generate a detection result, wherein the supply voltage is provided to an output stage in the signal processing circuit. The calibration circuit is configured to calculate a digital compensation value according to the detection result, wherein the digital compensation value is used for a digital processing circuit in the signal processing circuit to perform a DC offset calibration.

The technology described in this document can be embodied in an apparatus that includes an amplifier that includes a first Zeta converter connected to a power supply and a load. The amplifier also includes a second Zeta converter connected to the power supply and the load. The second Zeta converter is driven by a complementary duty cycle relative to the first Zeta converter. The amplifier also includes a controller to provide an audio signal to the first Zeta converter and the second Zeta converter for delivery to the load.

The technology described in this document can be embodied in an apparatus that includes an amplifier that includes a first Zeta converter connected to a power supply and a load. The amplifier also includes a second Zeta converter connected to the power supply and the load. The second Zeta converter is driven by a complementary duty cycle relative to the first Zeta converter. The amplifier also includes a controller to provide an audio signal to the first Zeta converter and the second Zeta converter for delivery to the load.

Embodiments of the invention provide for methods for automatically controlling loudness of an audio signal. Embodiments of the invention also provide for a device for automatically controlling loudness of an audio signal. In particular, the invention relates to controlling loudness of an audio signal to be replayed within a vehicle, such as a car.

Example embodiments provide a process that includes one or more of receiving an audio signal at a feedback compressor circuit, receiving an auxiliary attenuation signal from an auxiliary attenuation source, determining a threshold power level based on a value of the auxiliary attenuation signal, determining an output power level of the audio signal exceeds the threshold power level, combining the audio signal with the auxiliary attenuation signal from the auxiliary attenuation source and a compressed attenuation signal from the feedback compressor circuit to create a combination signal, and generating an audio output signal of the feedback compressor circuit based on the combination signal.

The technology described in this document can be embodied in an apparatus that includes an amplifier that includes a first Zeta converter connected to a power supply and a load. The amplifier also includes a second Zeta converter connected to the power supply and the load. The second Zeta converter is driven by a complementary duty cycle relative to the first Zeta converter. The amplifier also includes a controller to provide an audio signal to the first Zeta converter and the second Zeta converter for delivery to the load.