Abstract: A thermal sensor at the output of a switching amplifier senses heat dissipation at the output switch. If an overheating condition is sensed, gain of the digital input signal is lowered to reduce output power of the audio output signal.

Abstract: A thermal sensor at the output of a switching amplifier senses heat dissipation at the output switch. If an overheating condition is sensed, gain of the digital input signal is lowered to reduce output power of the audio output signal.

Abstract: A thermal sensor at the output of a switching amplifier senses heat dissipation at the output switch. If an overheating condition is sensed, gain of the digital input signal is lowered to reduce output power of the audio output signal.

Abstract: A digital amplifier contains a circuit for converting the onset of a clipping condition into a missed pulse in a pulse width modulated pulse train generated from an analog signal and an improved circuit for producing a control voltage proportional to the extent of the clipping condition, which circuit includes a pulse counter for counting a predetermined number of missed pulses in the pulse train and a voltage generator for producing a voltage proportional to the extent of clipping when said predetermined number of missed pulses occurs. The generated voltage is applied to an attenuator for attenuating the analog input signal.

Abstract: A digital delay system employs a phase-locked loop to control a recall address generator. The phase-locked loop comprises a subtractor for determining the difference between the store address and the recall address and for producing a phase signal corresponding to this difference. The phase signal is directed to a voltage controlled oscillator for controlling the rate at which the recall address generator recalls data from a memory. A delay length is introduced as a phase error into the phase-locked loop. Input data is stored in a memory at a fixed rate, and recalled from the memory at a rate determined by the phase-locked loop. When the error signal is zero, the recall address rate will equal the store address rate and the respective addresses will be equal.

Abstract: A digital amplifier having a modulator for transforming the analog audio input signal into two complimentary trains of pulse width modulated signals for driving the power switches, which modulator utilizes a precision triangular waveform to control the transformation. The modulator employs all differential processing without saturated transistors to achieve a minimal distortion modulation system. Upon the occurrence of over-modulation, pulses from the width modulated pulse train produced by the modulator are dropped, and the resulting loss of pulses is detected and fed back to a variable gain amplifier stage of the system. The distortion detection system for detecting the missing pulses utilizes a timing network to establish the missing pulse period necessary to begin input attenuation of the audio signal by the variable gain amplifier stage.

Abstract: A digital amplifier having a modulator for transforming the analog audio input signal into two complimentary trains of pulse width modulated signals for driving the power switches, which modulator utilizes a precision triangular waveform to control the transformation. The modulator employs all differential processing without saturated transistors to achieve a minimal distortion modulation system. Upon the occurrence of overmodulation, pulses from the width modulated pulse train produced by the modulator are dropped, and the resulting loss of pulses is detected and fed back to a variable gain amplifier stage of the system. The distortion detection system for detecting the missing pulses utilizes a timing network to establish the missing pulse period necessary to begin input attenuation of the audio signal by the variable gain amplifier stage.