A multiple power mode amplifier provides a low and a high power mode
without using switches. This amplifier may be used in radio frequency
(RF) applications such as mobile telephones, pagers, portable digital
assistants, and wireless e-mail devices. In the low power mode, the power
consumption of the amplifier is reduced, which will increase operation
time, especially important for battery-operated devices. In one
implementation, the amplifier includes a number of impedance matching
network units (130, 140, 150, and 160), impedance transformer (170), and
a power stage (120). An implementation provides further power consumption
savings by modulating a bias of an amplifier stage.