Control of distortion in a line-powered amplifier with a rail-to-rail output voltage swing.

摘要

Distorsion control in a push-pull output stage of a speech amplifier of a telephone powered through the telephone line is more effectively and advantageously implemented by independently sensing an eventual state of saturation reached by any of the two output transistors (PWH,PWL) of the amplifier, summing the current signals ( epsilon ) representative of the sensed state of saturation of either or both output transistors, integrating (RC) the resulting sum current signal to produce a DC signal and using the DC signal for activating an AGC loop. The DC signal indiscriminately accounts for any cause of saturation, though virtually representing the level of the amplified AC signal. Distorsion may be controlled without penalizing output voltage swing and power consumption.