Dynamic voltage scaling for series hybrid amplifiers

Abstract

We present an optimization of the voltage scaling algorithm in low power audio class G amplifier for headphones application to allow longer playback time. The optimization approach minimizes the voltage difference between the internal audio amplifier power supply and its output signal over a large range of operating conditions. The modeling is based on a behavioral model enabling accurate and rapid evaluation of efficiency and audio quality with realistic input stimuli. The model validated in practice is used to optimize the voltage scaling using only few power supply levels. Thanks to a global search algorithm followed by a local one, the optimization gives the better parameters for voltage scaling algorithm while keeping a good audio quality. The proposed configuration increases the efficiency up to 48% at nominal operation.

Predicting the Impact of Magnetic Components Used for EMI Suppression on the Base-Band of a Power Amplifier

“…In addition, at this current level the magnetic material is saturated, but in fact, at current levels lower than the component rated current, the material would also be saturated (saturation appears for currents higher than 20 mA). Note also that in real audio signals, the crest factor (crest f actor = peak value/rms value) is generally higher than the one of a sinusoidal signal [33]. The peak value is then considerably higher than the rms current.…”

Power Efficiency and EMI Attenuation Optimization in Filter Design

“…Therefore, due to the EMI filter, the system consumes 5 times more at low output power. In [2], it has been shown that in a real audio signal (i.e. Jazz song), there are more amplitude levels lower than -20 dB full scale than the higher amplitudes for a 10 s recording.…”