Adaptive rail amplifier (ARA) technology
View Patent ↗An efficient class-G amplifier having multiple rails is configured with parallel class AB amplifiers powered by at least one rail supplying a voltage that can be varied in response to signal characteristics, typically as sensed at an output across a load. In a specific embodiment, an analog-to-digital converter is coupled to a digital signal processor that converts signals into a programmed voltage level for setting the voltage rail.
1. A linear signal amplifier for amplifying a signal at a load comprising:
a first power rail;
a second power rail
a first class AB amplifier having a first power supply at the first power rail;
a second class AB amplifier having a second power supply at the second power rail;
a level detector for sensing signal power;
an analog to digital converter for converting an analog output of the level detector to a digitized value representative of the signal power;
a digital signal processor coupled to receive the digitized value and to select a power rail;
a digital to analog converter for setting power level on the second power rail; and
switching means responsive to the power level and coupled to alternately switch input signal paths to output signal paths between the first class AB amplifier and the second class AB amplifier in response to said digital to analog converter.
2. The amplifier according to claim 1 wherein said level detector is coupled to the load to monitor amplifier output signal power for controlling power switching.
3. The amplifier according to claim 1 wherein said second power rail has a maximum voltage less than a minimum voltage of said first power rail.
4. The amplifier according to claim 1 wherein said digital to analog converter comprises a comparator for generating a 1-bit signal to switch between said first power rail and said second power rail.