A mobile wireless communication device comprising: a signal modifier in said mobile wireless communication device to receive an input signal and produce a first transmit signal differing by a diversity parameter adjustment from a second transmit signal; and a transmit amplifier stage in said mobile wireless communication device operable to amplify said first and second transmit signals, comprising: a first channel comprising at least one first power amplifier operable to provide power to amplify the first transmit signal for transmission by a first antenna at a first fractional power, wherein a substantially maximum efficiency of the first power amplifier substantially coincides with the first fractional power, the first fractional power being a first fraction of a specification power limit of the wireless device; and a second channel comprising at least one second power amplifier operable to amplify the second transmit signal for transmission by a second antenna at a second fractional power, wherein a substantially maximum efficiency of the second power amplifier substantially coincides with the second fractional power, the second fractional power being a second fraction of the specification power limit of the wireless device, wherein said signal modifier is further to produce said diversity parameter adjustment based on a feedback signal received from a receiver of said first and second transmit signals. a signal modifier in said mobile wireless communication device to receive an input signal and produce a first transmit signal differing by a diversity parameter adjustment from a second transmit signal; and a transmit amplifier stage in said mobile wireless communication device operable to amplify said first and second transmit signals, comprising: a first channel comprising at least one first power amplifier operable to provide power to amplify the first transmit signal for transmission by a first antenna at a first fractional power, wherein a substantially maximum efficiency of the first power amplifier substantially coincides with the first fractional power, the first fractional power being a first fraction of a specification power limit of the wireless device; and a second channel comprising at least one second power amplifier operable to amplify the second transmit signal for transmission by a second antenna at a second fractional power, wherein a substantially maximum efficiency of the second power amplifier substantially coincides with the second fractional power, the second fractional power being a second fraction of the specification power limit of the wireless device, a first channel comprising at least one first power amplifier operable to provide power to amplify the first transmit signal for transmission by a first antenna at a first fractional power, wherein a substantially maximum efficiency of the first power amplifier substantially coincides with the first fractional power, the first fractional power being a first fraction of a specification power limit of the wireless device; and a second channel comprising at least one second power amplifier operable to amplify the second transmit signal for transmission by a second antenna at a second fractional power, wherein a substantially maximum efficiency of the second power amplifier substantially coincides with the second fractional power, the second fractional power being a second fraction of the specification power limit of the wireless device, wherein said signal modifier is further to produce said diversity parameter adjustment based on a feedback signal received from a receiver of said first and second transmit signals.