Multi-output switching amplifier

This application claims priority from U.S. Provisional Patent Application Ser. No. 60/494,215, filed Aug. 11, 2003, the entire content of which is incorporated herein by reference.

This invention relates generally to switching amplifiers and, in particular, to the use of a single pulsewidth modulator to drive multiple output stages.

High-quality amplifier design through the analog era has largely relied upon feedback to ensure linear operation and mitigate errors introduced at each stage of an amplifier. Although the migration into digital switching amplification has followed the closed-loop design model, newer technologies are becoming available which facilitate high quality open-loop amplification without imposing the cost penalty associated with equivalent analog approaches. In certain application areas, such as distributed amplification, it is possible to leverage the lack of feedback loop complexity into an additional cost saving.

The present invention resides in apparatus and methods for driving multiple output stages with a single switching amplification modulator, thereby reducing system cost. The technique also addresses applications wherein one or more of several output stages of potentially differing output powers are desired at one time. That is, the switching drivers and loads can be the same or different.

FIG. 1 is a block diagram depicting a preferred embodiment of the invention.

The present invention is a method of driving multiple output stages with a single switching amplification modulator, thereby reducing system cost. FIG. 1 shows a preferred embodiment. Incoming digital data stream 101 is fed to pulsewidth modulator 102 , which converts the data stream 101 into pulsewidth modulated signals suitable for driving switching output drivers.

The pulsewidth modulated signals are connected to switch 103 and switching output drivers 105 and 106 . The output of switch 103 connects to the input of switching driver 104 , making its output optional. The amplified power outputs of switching drivers 104 , 105 , and 106 are connected to loads 107 , 108 , and 109 , respectively. Thus, a single amplifier modulator can then be seen to drive multiple output stages, thereby reducing system cost. Note that this technique also addresses applications wherein one or more of several output stages of potentially differing output powers are desired at one time. That is, the switching drivers 104 , 105 , and 106 and loads 107 , 108 , and 109 can be the same or different.