1. A communication device having a system for dynamically varying the operating current of at least part of a multi-mode transmitter comprising: a mode selector for selecting a mode of operation of the multi-mode transmitter, wherein the mode selector is configured to select a mode responsive to a command received over a user interface; and a controller that adjusts the operating current of at least part of the multi-mode transmitter responsive to the mode selector, the controller further including first, second, and third sub-modules, wherein the first sub-module is configured to determine a base linearity responsive to the selected mode, where the base linearity is responsive to a crest factor associated with the selected mode, the second sub-module is configured to adjust the base linearity responsive to a desired transmit power, and the third sub-module is configured to determine the operating current responsive to the adjusted base linearity.