Monolithic Power Systems, Inc.

Pacifictech Microelectronics, Inc.

Diodes Inc.

National Semiconductor Corporation

Hideto Takagishi

Alan Wu

Wolf Zhang

Huey Nguyen

Simon Tsai

A circuit receives a first input signal and a second input signal, and provides three driving signals to three output wires, respectively. A first driving signal is provided to a first output wire, and is based on a difference between the first input signal and the second input signal. A second driving signal is provided to a second output wire, and is based on a sum of the first input signal and the second input signal. A third driving signal is provided to a third output wire, and is based on an inverse of the first driving signal. A first output signal between the first output wire and the second output wire is based on the second input signal. A second output signal between the third output wire and the second output wire is based on the first input signal.

Stereo audio system and method

In one embodiment the present invention includes a switching circuit. The circuit comprises a first transistor, a second transistor, and a boost circuit. The first transistor couples a first power source to a first intermediate node during a first phase of operation and the second transistor couples a second intermediate node to the first intermediate node during a second phase of operation. The boost circuit is coupled to the second intermediate node and provides a second power source by a transferring of energy from the first power source. The transferring of energy includes an inductor receiving energy from the first power source during the first phase of operation and providing a portion of said energy to the boost circuit during the second phase of operation. The boost circuit provides a biasing to enable deactivation of the second transistor during the first phase of operation.

Switching supply circuits and methods

Embodiments of the present invention include switching amplifier circuits and methods. In one embodiment, the present invention includes a low distortion method of driving a switching amplifier comprising modulating an audio input signal to produce a half-wave rectified pulse-width modulated signal and a complementary half-wave rectified pulse-width modulated signal. These signals may be amplified in a power amplifier and combined in a feedback circuit to generate a first feedback signal and a second feedback signal, which may be coupled the inputs of a modulator for controlling the output signal.

Low distortion switching amplifier circuits and methods

Embodiments of the present invention include switching amplifier circuits and methods. In one embodiment, the present invention includes an low distortion method of driving a switching amplifier comprising generating a first pulse width modulated signal on a first terminal, generating a second pulse width modulated signal on a second terminal, and delaying one of the first or second signals. In one embodiment, the modulated signals and delay result in pulse trains near zero crossings to reduce crossover distortion.

In one embodiment, the present invention includes a circuit comprising an amplifier having an input terminal, an output terminal, a positive supply voltage, and a negative supply voltage. The amplifier is configured to have a first gain. A variable feedback circuit is coupled between the input terminal and the output terminal. The difference between the voltage on the output terminal and input terminal is received by the variable feedback circuit, which changes the gain of the circuit and reduces distortion.

Variable feedback circuits and methods

The present disclosure introduces a simple method and apparatus for a Class-D amplification and Pulse Width Modulation (PWM) of an input signal, such as a voice signal. The proposed circuits do not require reference input signals such as triangular signals; rather, the combination of the circuits' self-oscillating device arrangements and the delay elements performs pulse width modulation at higher frequencies while producing less noise. Among other advantages, these circuits offer shorter response time, less distortion, better power supply ripple rejection, larger negative feedback, and simpler construction. The recommended Class-D amplifiers can be used with speakers and can have single-ended or differential input.

Method and apparatus for self-oscillating differential feedback class-D amplifier

A Class D amplifier circuit performs audio signal processing and other signal processing by using a bang-bang controller and a noise-shaping feedback network. The bang-bang controller triggers generation of a rectangular waveform that corresponds to changes in a control signal derived from an input analog signal, with the generation of the rectangular waveform being based on a comparison of the control signal with another signal derived from hysteresis associated with an output of a comparator. A filter filters the rectangular waveform to obtain an amplified output analog signal substantially representative of the input analog signal. The feedback network noise shapes the output analog signal, and feeds back the noise-shaped output analog signal and substracts it from the input analog signal.

Class D audio amplifier

A battery charger is provided that does not sink current from the battery during a reverse mode of operation. The battery charger includes upper and lower switching circuits, which alternately activate and deactivate to provide outgoing current flow. A comparator is coupled to the lower switching circuit to detect current flow into the upper and lower switching circuits. If this current flow is detected, a control circuit is provided that will deactivate the lower switching circuit to prevent subsequent incoming current flow. Further, a transistor is coupled to the lower switching circuit to detect the incoming current flow.

Battery charger

A circuit for generating an accurate reproduction of the output of a Class D amplifier for error-correction purposes includes a reference signal amplifier circuit. The reference signal amplifier circuit includes an op-amp configured as a differential amplifier that combines the digital outputs of the internal output stage of the amplifier into a single reference signal. By reducing the bandwidth of the op-amp, switching noise is removed from the digital signals, without adding any phase shift to the generated reference signal. In addition, by using the digital signals directly from the output stage rather than the filtered analog outputs of the amplifier, distortion due to external speaker-induced back-EMF is prevented. The reference signal can then be compared to the original signal input to the amplifier for error-correcting purposes.

Growing community of inventors

San Jose, CA, United States of America

Hideto Takagishi