Patent classifications
H03G3/345
Amplifier-based microphone shutoff system
An amplifier-resident device for protecting amplifiers and loudspeakers from shock transient audio signals from dropped microphones that may use either an amplifier control signal from the microphone or a sequential sampling of the incoming audio (optionally switchable) to determine if a microphone drop, or other shock transient, is occurring. If a shock transient is occurring, the device blocks audio signal access to the amplifier. The audio signal goes through a delay line to allow processing time for detecting a shock transient and switching the shock transient audio signal out of the path to the amplifier. The delay may be variable. The device may be integral to the amplifier or may plug into a microphone jack of the amplifier, allowing use with legacy amplifiers. In an embodiment, the device may store safe, predetermined audio signals to send to the amplifier during, and in place of, a shock transient.
METHODS AND CIRCUITS TO REDUCE POP NOISE IN AN AUDIO DEVICE
A class D amplifier receives and amplifies a differential analog signal which is then differentially integrated. Two pulse width modulators generate pulse signals corresponding to the differentially integrated analog signal and two power units generate output pulse signals. The outputs the power units are coupled to input terminals of integrators via a resistor feedback network. An analog output unit converts the pulse signals to an output analog signal. The differential integration circuitry implements a soft transition between mute/un-mute. In mute, the integrator output is fixed. During the soft transition, the PWM outputs change slowly from a fixed 50% duty cycle to a final value to ensure that no pop noise is present in the output as a result of mode change.
Methods and circuits to reduce pop noise in an audio device
A class D amplifier receives and amplifies a differential analog signal which is then differentially integrated. Two pulse width modulators generate pulse signals corresponding to the differentially integrated analog signal and two power units generate output pulse signals. The outputs the power units are coupled to input terminals of integrators via a resistor feedback network. An analog output unit converts the pulse signals to an output analog signal. The differential integration circuitry implements a soft transition between mute/un-mute. In mute, the integrator output is fixed. During the soft transition, the PWM outputs change slowly from a fixed 50% duty cycle to a final value to ensure that no pop noise is present in the output as a result of mode change.