| 摘要 |
An envelope tracking supply modulator comprises a switch mode path 24 and a linear amplifier path 70 that includes plural amplifiers 781 to 78n, each having an output stage of a different size. At least one of the plural amplifiers is enabled in dependence on an output power. Amplifiers may be enabled depending on required output power such as the average power determined for a transmission slot. Outputs of the linear amplifiers may be combined with the output of the switch mode path in a summer 29. Linear amplifiers 78 may correct an error in the switch mode path, and provide a modulated supply voltage to one or a plurality of amplifiers 17 of different sizes, each associated and enabled with one of the linear amplifiers as a pair. Each amplifier may be differently sized to provide different peak current capability and have compensation optimised for the size of its output stage. |
