Low-Power Modulation in an Amplifier

Abstract

A switching audio amplifier may include a modulation enhancement feature, in which the pulse-width modulated (PWM) signals driving the output stage are reduced or increased by identical step sizes to create an auxiliary PWM scheme representative of an idle (low-power) state of the input signal. The PWM signals, provided to a full-bridge power stage circuit for example, may be thereby reduced to another state to reduce power dissipation in a switch-mode power supply. By incrementally adjusting the PWM duty-cycle identically in all PWM signals to a value less than (or up to) 50%, the amount of current dissipated in the output load may be effectively controlled. The PWM pulses may be adjusted up or down, while checking for saturation corresponding to both minimum and maximum pulse-widths. A dampener circuit may be used to set the time between incremental adjustments, to further reduce audible pops and clicks.

Description

PRIORITY CLAIM[0001]This application claims benefit of priority of U.S. provisional application Ser. No. 61 / 543,998 titled “Circuits and Methods Used in Audio Signal Processing”, filed Oct. 6, 2011, which is hereby incorporated by reference in its entirety as though fully and completely set forth herein.FIELD OF THE INVENTION[0002]The present invention relates generally to signal processing, and more particularly performing low-power modulation in an amplifier.DESCRIPTION OF THE RELATED ART[0003]Signal processing represents a combined application of electrical / computer engineering and mathematical principles, primarily directed to the analysis of and operation on either discrete or continuous time signals. Signals of interest can include sound, images, time-varying measurement values and sensor data, for example biological data such as electrocardiograms, control system signals, telecommunication transmission signals such as radio signals, and many others. Signals are typically anal...

AI Technical Summary

Benefits of technology

The patent describes an audio amplifier with a feature to prevent power loss during switching and conduction. This is achieved by implementing a low-power modulation scheme called deterministic pulse-width modulation, which eliminates certain signals during the switching process. The amplifier can be either a class-BD or a class-AD amplifier, depending on the input format. The modulation enhancement can be achieved by adjusting the duty-cycle of the signals sent to the power stage circuit, reducing the power dissipation and current dissipated in the output load. This technique helps recover all switching and conduction losses in the power stage circuit. Additionally, the duty-cycles can be adjusted to avoid transients and perturbations on the outputs. Overall, this patent describes a way to improve the efficiency and performance of audio amplifiers.

Problems solved by technology

This permits signal processing using digital circuits such as microprocessors and computers, and while analog to digital conversion can be prone to loss, most modern audio systems use the digital approach because digital signal processing techniques are overall more powerful and efficient than signal processing in the analog domain.

The quality and operating precision of these components directly impacts the quality of audio signal processing systems, as designers have to continually overcome numerous difficult design challenges to meet required specifications and quality standards.

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