Abstract: A power conversion system includes a feedback controller circuit connected between the output of a boost converter and a duty cycle control input of the boost converter. The feedback controller circuit comprises: a first summing node which generates an error signal indicative of a difference between a voltage of the output of the boost converter and a reference voltage, a compensator circuit receiving the error signal and applying a gain to the error signal to generate an amplified error signal, and a scaling circuit for scaling the amplified error signal to generate a scaled signal, which is applied to a duty cycle control input of the boost converter to alter the duty cycle and/or pulse frequency of the boost converter. The feedback controller circuit provides a frequency-dependent impedance transformation looking into the boost converter from the source such that instability due to line impedance is reduced.

Abstract: An apparatus includes a member configured to form an acoustic seal around a portion of an acoustic environment, and active noise reduction circuitry. The active noise reduction circuitry includes: detection circuitry configured to detect a change in pressure within the acoustic environment caused by movement of the member, and gain compensation circuitry configured to change a loop gain of a feedback loop in response to the detected change in pressure.

Abstract: In an aspect, in general, a feedback based active noise reduction system is configured to detect actual or potential instability by detecting characteristics of the system related to potential or actual unstable behavior (e.g., oscillation) and adapt system characteristics to mitigate such instability.

Abstract: An apparatus includes a member configured to form an acoustic seal around a portion of an acoustic environment, and active noise reduction circuitry. The active noise reduction circuitry includes: detection circuitry configured to detect a change in pressure within the acoustic environment caused by movement of the member, and gain compensation circuitry configured to change a loop gain of a feedback loop in response to the detected change in pressure.

Abstract: In an aspect, in general, a feedback based active noise reduction system is configured to detect actual or potential instability by detecting characteristics of the system related to potential or actual unstable behavior (e.g., oscillation) and adapt system characteristics to mitigate such instability.