Method and apparatus for reducing power dissipation in multi-carrier amplifiers

DETAILED DESCRIPTION OF THE DRAWINGS The features and advantages of the present invention outlined above are described more fully below in the detailed description in conjunction with the drawings where like reference numerals refer to like elements throughout.
FIG.
1 is a function block diagram showing an example discrete multi-tone (DMT) system in which the present invention may be employed; FIG.
2 is a graph illustrating the principle of a multi-carrier system; FIG.
3 is a simplified illustration of a line driver in a digital subscriber line environment; FIG.
4 is a simplified diagram of an amplifier circuit that may be employed as a line driver, a power amplifier, etc.
; FIG.
5 is a graph showing a normal distribution of multi-carrier modulator output signals; FIG.
6 is a graph plotting a lower supply voltage (in volts) against power dissipation (in %) assuming a fixed high supply voltage in accordance with the present invention; FIG.
7 is a diagram showing a first example embodiment of the present invention; FIG.
8 is a diagram showing a second example embodiment of the present invention; FIG.
9 shows a digital implementation of a switch control signal that may be employed in the present invention; FIG.
10 shows an analog implementation for generating a switch control signal for use in the present invention; and FIG.
11 is a graph showing the amplifier circuit supply voltage plotted with the output voltage of the amplifier circuit in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION In the following description, for purposes of explanation and not limitation, specific details are set forth such as particular embodiments, circuits, circuit components, etc.
in order to provide a thorough understanding of the present invention.
However, it will be apparent to one skilled in the art that the present invention may be practiced in other embodiments that depart from these specific details.
In other instances, detailed descriptions of well-known methods, devices, and circuits are omitted so as not to obscure the description of the present invention with unnecessary detail