Abstract: The technology described in this document can be embodied in an audio power amplifier that includes a first channel and a second channel. Each of the first channel and the second channel includes an input to receive an input signal, a pair of switching devices, drive circuitry for driving the pair of switching devices to produce a signal, and an output filter to filter the signal from the pair of switching devices. The output filter is configured to provide the filtered signal to an audio load. Each of the first channel and the second channel includes a voltage feedback loop to provide a voltage of the filtered signal to a voltage controller of the audio power amplifier, and a current feedback loop to provide a current of the filtered signal to a current controller of the audio power amplifier. The audio power amplifier includes a summer for combining the input of the first channel and the input of the second channel when an output of the first channel is connected to an output of the second channel.

Abstract: The technology described in this document can be embodied in an audio power amplifier that includes a pair of switching devices, drive circuitry for driving the pair of switching devices to produce a signal, and an output filter to filter the signal from the pair of switching devices. The output filter is configured to provide the filtered signal to an audio load. The audio power amplifier includes a voltage feedback loop to provide a voltage of the filtered signal to a voltage controller of the audio power amplifier, and a current feedback loop to provide a current of the filtered signal to a current controller of the audio power amplifier.

Abstract: The technology described in this document can be embodied in an audio power amplifier that includes a first channel and a second channel. Each of the first channel and the second channel includes an input to receive an input signal, a pair of switching devices, drive circuitry for driving the pair of switching devices to produce a signal, and an output filter to filter the signal from the pair of switching devices. The output filter is configured to provide the filtered signal to an audio load. Each of the first channel and the second channel includes a voltage feedback loop to provide a voltage of the filtered signal to a voltage controller of the audio power amplifier, and a current feedback loop to provide a current of the filtered signal to a current controller of the audio power amplifier. The audio power amplifier includes a summer for combining the input of the first channel and the input of the second channel when an output of the first channel is connected to an output of the second channel.

Abstract: The technology described in this document can be embodied in an audio power amplifier that includes a pair of switching devices, drive circuitry for driving the pair of switching devices to produce a signal, and an output filter to filter the signal from the pair of switching devices. The output filter is configured to provide the filtered signal to an audio load. The audio power amplifier includes a voltage feedback loop to provide a voltage of the filtered signal to a voltage controller of the audio power amplifier, and a current feedback loop to provide a current of the filtered signal to a current controller of the audio power amplifier.

Abstract: Example circuitry includes: a transformer circuit having first windings and second windings, where the second windings are magnetically orthogonal to the first windings; first transistors to provide a first voltage to a load, where each of the first transistors is responsive to a first control signal that is based on a first signal through a first winding; second transistors to provide a second voltage to the load, where each of the second transistors is responsive to a second control signal that is based on the first through the first winding, and where the first and second control signals cause the first transistors to operate in a different switching state than the second transistors; and control circuitry responsive to signals received through the second windings to control the first transistors and the second transistors to operate in a same switching state.

Abstract: Example circuitry includes: a transformer circuit having first windings and second windings, where the second windings are magnetically orthogonal to the first windings; first transistors to provide a first voltage to a load, where each of the first transistors is responsive to a first control signal that is based on a first signal through a first winding; second transistors to provide a second voltage to the load, where each of the second transistors is responsive to a second control signal that is based on the first through the first winding, and where the first and second control signals cause the first transistors to operate in a different switching state than the second transistors; and control circuitry responsive to signals received through the second windings to control the first transistors and the second transistors to operate in a same switching state.

Abstract: An apparatus for driving speakers includes user-configurable amplifier cells for driving selected speakers, a synchronous rectifier circuit, and a control system. Each cell connects between power rails. The rectifier circuit provides current on the rails for consumption by the cells. The current depends on the configuration. The control system implements a model of the rectifier circuit and cells and uses it to control an audio input signal in response to information concerning electrical outputs of the amplifier cells. This indirectly limits current drawn from the synchronous rectifier circuit.

Abstract: An apparatus for driving speakers includes user-configurable amplifier cells for driving selected speakers, a synchronous rectifier circuit, and a control system. Each cell connects between power rails. The rectifier circuit provides current on the rails for consumption by the cells. The current depends on the configuration. The control system implements a model of the rectifier circuit and cells and uses it to control an audio input signal in response to information concerning electrical outputs of the amplifier cells. This indirectly limits current drawn from the synchronous rectifier circuit.

Abstract: An apparatus and associated method for observing an analog position signal of a control object in relation to positional indicia, recalling a previously stored runout correction value associated with the positional indicia, and calculating a corrected position signal for the control object in relation to the position signal and the runout correction value.

Abstract: A method and apparatus for dealing with undesired deviations of servo burst component magnitudes, as compared with nominal magnitudes, is provided. Inaccurate servo burst magnitudes can arise from components which are misplaced, often from an inaccuracy in a trimming operation. In one aspect, a value indicative of the shift of a component null point is measured and used to calculate a burst amplitude correction factor. Knowledge of system dynamics can be used to calculate a track shape that can be used in calculating the correction factor. Values indicative of track shape can be related to transfer functions of the disk drive controller and plant. In one embodiment, information indicative of repeatable runout is convolved with a function of the transfer function of the controller and plant, and the result is used for calculating a burst component amplitude correction value.

Abstract: An apparatus and associated method for observing an analog position signal of a control object in relation to positional indicia, recalling a previously stored runout correction value associated with the positional indicia, and calculating a corrected position signal for the control object in relation to the position signal and the runout correction value.