Texas Instruments Corporation

Kim Nordtorp Madsen

Shun Qian

Lucia Wan

Lars Risbo

Thomas Holm Hansen

Claus Niels Neesgaard

Anker Bjørn-Josefsen

Allan Nogueras Nielsen

Søren Bang Poulsen

The disclosed embodiments include an audio amplifier system configured to provide a total harmonic distortion (THD) controlled clip detector and an automatic gain limiter (AGL) solution for a closed-loop amplifier. The audio amplifier system is capable of maintaining high power output without hard distortion (i.e., hard clipping) for providing better acoustics, while preventing damage to the system.

Total harmonic distortion (THD) controlled clip detector and automatic gain limiter (AGL)

A predictive back-emf protection methodology for an electromechanical system, including a signal processor that processes a source signal to provide a modified source signal, a driver that converts the modified source signal to a drive signal, and an electromechanical transducer that generates, from the drive signal, a transducer response, and a back-emf signal coupled back to the driver output. A predictive back-emf generator (such as a routine in the signal processor) is characterized by a back-emf transfer function (linear parameterized model of the electromechanical transducer) for transforming an input signal into a transform back-emf representation of a back-emf signal predicted by the back-emf transfer function as a response of the electromechanical transducer to such input signal. The signal processor processes the source signal based on the transform back-emf representation to generate the modified source signal input to the driver. An example application is limiting peaking current in an audio system.

Electromechanical system with predictive back-EMF protection

A fixed frequency class-D audio amplifier includes the L-C output filter in a high order feedback loop. An audio amplifier integrated circuit includes an output driver, an output terminal, a first input terminal, a second order filter, and a summing amplifier. The output driver is configured to drive a speaker coil through an L-C filter. The output terminal is to couple the output driver to an input side of the L-C filter. The first input terminal is to couple an output side of the L-C filter to the integrated circuit. The second order filter includes a first filter stage, and a second filter stage coupled to an output of the first filter stage. The summing amplifier includes a first input coupled to the first input terminal, and a second input coupled to an output of the second filter stage.

Class-D amplifier with post filter feedback loop

Conventional muting circuitry for amplifiers (which usually uses clamps) generally has about 20-30 dB of attenuation. Here, an integrated circuit or IC is provided that includes an amplifier, switch networks, and a controller. The controller provides control signals to the switch network to provide mute functionality by actively muting the amplifier. In particular, feedback is provided through at least one of the switch networks to drive the output of the amplifier to null or ground so as to provide 70-80 dB (or more) of attenuation.

Active mute scheme for an amplifier

An amplifier system can include a biasing amplifier that provides a first amplified signal to a DC blocking element that is connected with a load based on a first control signal. A power amplifier provides a second amplified signal for driving the load based on a second control signal. A control system controls the biasing amplifier to charge the DC blocking element so as to mitigate a voltage drop across the load (e.g., to substantially eliminate audible artifacts) when the power amplifier is activated to provide the second amplified signal.

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Skovlunde, Denmark

Kim Nordtorp Madsen