Embodiments of the present disclosure provide a current amplification circuitry and a driving method thereof, and a fingerprint detection device. The current amplification circuitry includes a voltage control circuit, a plurality of first current amplification circuits, and a second current amplification circuit. The voltage control circuit provides a voltage control signal to the plurality of first current amplification circuits. The first current amplification circuit includes a current mirror, and the current mirror is coupled to a voltage input terminal, the voltage control circuit, and a first input terminal of the second current amplification circuit. The first current amplification circuit amplifies a current from the voltage input terminal according to the voltage control signal provided by the voltage control circuit, and provides the amplified current to the second current amplification circuit. The second current amplification circuit is coupled to the voltage input terminal via a second input terminal and amplifies the amplified current.

An amplifying device includes a first amplifier, a voltage-limiting circuit, a second amplifier, a first controller, and a second controller. The first amplifier is configured to amplify an input signal. The voltage-limiting circuit is configured to limit a voltage of an output signal from the first amplifier to within a limit range. The second amplifier is configured to amplify an output signal from the voltage-limiting circuit. The first controller is configured to control the limit range in accordance with a current supplied to a load from the second amplifier. The second controller is configured to decrease an amplification factor of the first amplifier in a state in which the voltage-limiting circuit limits the voltage of the output signal from the first amplifier.

A Class-D amplifier having a low power dissipation mode includes first and second independent output stages that receive respective first and second level power supply voltages for driving a load coupled to the amplifier output during respective first and second operating modes. Bypass switches are controllable to disconnect the second output stage from the output during the first operating mode and to connect the second output stage to the output during the second operating mode. The operating modes are selected based on the amplifier output power level. First and second independent pre-driver stages receive the respective first and second level power supply voltages for driving the respective first and second independent output stages. During the second operating mode the first pre-driver stage is placed into a low power dissipation state and during the first operating mode the second pre-driver stage is placed into a low power dissipation state.

Amplifier systems for measuring a wide range of current are provided herein. In certain embodiments, an amplifier system includes a controllable sensing circuit, a first amplifier including an output configured to drive a device under test (DUT) through the controllable sensing circuit, and a second amplifier including an input coupled to the controllable sensing circuit and operable to generate a measurement signal indicating an amount of measured current of the DUT. The amplifier system further includes a control circuit operable to control a configuration or mode of the controllable sensing circuit suitable for a particular type of DUT.

The present disclosure relates to a current detecting apparatus using an operational amplifier and a method thereof. In accordance with an aspect of the present disclosure, there is provided a current detecting apparatus of a conductor including: a shunt resistor connected to the conductor; an operational amplifier connected to the shunt resistor; a first resistor connected between the shunt resistor and a first input terminal of the operational amplifier; a second resistor connected between the shunt resistor and a second input terminal of the operational amplifier; a third resistor connected between a ground and the first input terminal of the operational amplifier; and a fourth resistor connected between the ground and the second input terminal of the operational amplifier.

A system includes a power regulator coupled between a coil and a battery, wherein the power regulator is configured as a linear regulator when power is provided from the coil to the battery, and a current sense apparatus having two inputs coupled to an input and an output of the power regulator, respectively, wherein the current sense apparatus is configured to sense a bidirectional current flowing through the power regulator.

Herein disclosed in some embodiments is a fault detector for power amplifiers of a communication system. The fault detector can detect a portion of the power amplifiers that are in fault condition and can prevent or limit current flow to the power amplifiers in fault condition while allowing the rest of the power amplifiers to operate normally. The fault detector can further indicate which power amplifiers are in fault condition and/or the cause for the power amplifiers to be in fault condition. Based on the indication, a controller can direct communications away from the power amplifiers in fault condition and/or perform operations to correct the fault condition.

An audio signal control circuit includes an impedance calculator, a suppression value setter, a level detector, and a level controller. The impedance calculator is configured to calculate impedance of a speaker from voltage and current of an audio signal to be outputted to the speaker. The suppression value setter is configured to set a suppression value of the audio signal, using the impedance. The level detector is configured to perform level detection using: i) the voltage when the impedance is equal to or more than a switching threshold value, and ii) the current when the impedance is less than the switching threshold value. The level controller is configured to perform level control of the audio signal using: i) a level of a detection signal that has been detected by the level detector, and ii) the suppression value.

An envelope tracking supply modulator for a power amplifier is disclosed. The envelope tracking supply modulator comprises a multilevel push-pull converter. The multilevel push-pull converter comprises a control logic configured to generate a first and second control signals based on an envelope reference signal; a source multilevel converter configured to receive the first control signal and generate a source multilevel power supply signal; a sink multilevel converter configured to receive the second control signal and generate a sink multilevel power supply signal. The envelope tracking supply modulator further comprises a power recycling supply coupled to the sink multilevel converter; a low-pass filter coupled to outputs of the source and sink multilevel converters to filter the power supply signals generated from the source and sink multilevel converters.

A Class-D amplifier includes a plurality of power rails, a quantizer, and a driver stage. The quantizer and the driver stage have a combined gain. For each power rail of the plurality of power rails, the Class-D amplifier senses a voltage value for the power rail and determines a ramp amplitude based on the sensed voltage value. The Class-D amplifier concurrently switches from the driver stage using a first power rail to a second power rail of the plurality of power rails and switches from the quantizer using the ramp amplitude associated with the first power rail to using the ramp amplitude associated with the second power rail so that the combined gain is constant.