Abstract: Presented are circuits and methods for providing real-time short-circuit detection, capable of detecting a short-circuit prior to occurrence of an over-limit current event. Such a circuit can be used to provide real-time short-circuit detection for a switched-mode system for a switched-mode system having a pre-driver and a power stage, and includes a reference block for generating a reference voltage according to drive signals provided by the pre-driver, and a comparator, which may be a synchronized comparator. The comparator is configured to compare the reference voltage to a switching node voltage generated in a power stage of the switched-mode system, and to produce an output enabling detection of the short-circuit in the switched-mode system.

Abstract: A low quiescent current amplifier and driver having multiple amplifiers (e.g. Class AB and B amplifiers) work in concert to independently amplify all or a portion of a signal into multiple amplified signals combined into a unified signal. Operation of a second amplifier is slaved to operation of a first amplifier. Each amplifier may have its own feedback loop providing the same gain transfer function to align transitions of the multiple amplified signals. Operation of the first amplifier may be detected using a replica of a signal, stage or transconductance in the first amplifier. At the same threshold, operation of the first and second amplifiers may be transitioned, e.g., the second amplifier may transition between providing increasing or decreasing current and providing zero current while the first amplifier may transition between providing constant current and providing increasing or decreasing current.

Abstract: A noise reduction circuit for reducing the effects of low frequency noise such as wind noise in communications applications is described. In one embodiment, the noise reduction circuit features a high pass filter formed by exploiting the existing off-chip AC coupling capacitances in making the connection to the source of audio signals. The filter may be adaptive to environmental low frequency noise level through programming the shunt resistances. A low-noise wide dynamic range programmable gain amplifier is also described. Adaptive equalization of the audio signal is also described through the utilization of programmable front-end resistors and a back-end audio equalizer.

Abstract: A low quiescent current amplifier and driver having multiple amplifiers (e.g. Class AB and B amplifiers) work in concert to independently amplify all or a portion of a signal into multiple amplified signals combined into a unified signal. Operation of a second amplifier is slaved to operation of a first amplifier. Each amplifier may have its own feedback loop providing the same gain transfer function to align transitions of the multiple amplified signals. Operation of the first amplifier may be detected using a replica of a signal, stage or transconductance in the first amplifier. At the same threshold, operation of the first and second amplifiers may be transitioned, e.g., the second amplifier may transition between providing increasing or decreasing current and providing zero current while the first amplifier may transition between providing constant current and providing increasing or decreasing current.

Abstract: Presented are circuits and methods for providing real-time short-circuit detection, capable of detecting a short-circuit prior to occurrence of an over-limit current event. Such a circuit can be used to provide real-time short-circuit detection for a switched-mode system for a switched-mode system having a pre-driver and a power stage, and includes a reference block for generating a reference voltage according to drive signals provided by the pre-driver, and a comparator, which may be a synchronized comparator. The comparator is configured to compare the reference voltage to a switching node voltage generated in a power stage of the switched-mode system, and to produce an output enabling detection of the short-circuit in the switched-mode system.

Abstract: Disclosed is a high efficiency amplifier operable to substantially reduce electromagnetic interference (EMI). The high efficiency amplifier comprises an output stage to provide a high powered signal to a load. The high efficiency amplifier further comprises an overlap protection circuit to produce a timing non-overlap in a control signal for the output stage, and an edge control circuit to reduce a transient portion of the high powered signal to substantially reduce the EMI. The overlap protection circuit and the edge control circuit may be implemented with resistive source degeneration. Also disclosed is a related method. In one embodiment, the high efficiency amplifier and the related method may be incorporated into a cellular telephone or a mobile audio device.

Abstract: Disclosed is a high efficiency amplifier operable to substantially reduce electromagnetic interference (EMI). The high efficiency amplifier comprises an output stage to provide a high powered signal to a load. The high efficiency amplifier further comprises an overlap protection circuit to produce a timing non-overlap in a control signal for the output stage, and an edge control circuit to reduce a transient portion of the high powered signal to substantially reduce the EMI. The overlap protection circuit and the edge control circuit may be implemented with resistive source degeneration. Also disclosed is a related method. In one embodiment, the high efficiency amplifier and the related method may be incorporated into a cellular telephone or a mobile audio device.

Abstract: A noise reduction circuit for reducing the effects of low frequency noise such as wind noise in communications applications is described. In one embodiment, the noise reduction circuit features a high pass filter formed by exploiting the existing off-chip AC coupling capacitances in making the connection to the source of audio signals. The filter may be adaptive to environmental low frequency noise level through programming the shunt resistances. A low-noise wide dynamic range programmable gain amplifier is also described. Adaptive equalization of the audio signal is also described through the utilization of programmable front-end resistors and a back-end audio equalizer.