Patent ID: 7049886
Filing Date: 2006-05-23
Classification: H03F

Abstract:
1. A multiple power mode amplifier configured for use in a portable electronic device, the amplifier comprising: a driver to provide a power signal; a power stage transistor including an input node and an output node, the input node of the power stage transistor being coupled to the driver to receive the power signal from the driver in a high power mode; an impedance transformer including an input node and an output node and provided in a parallel branch to the power stage transistor, the input node of the impedance transformer being configured to receive the power signal from the driver in a low power mode; and a control circuit coupled to the power stage transistor and configured to apply a first control signal to the power stage transistor to place the power stage transistor in an off-state during the low power mode and a second control signal to the power stage transistor to place the power stage transistor in an on-state during the high power mode, wherein in the off-state, the power stage transistor directs the power signal from the driver primarily to a bypass path including the impedance transformer, and in the on-state, the power stage transistor directs the power signal from the driver primarily to a power stage path including the power stage transistor.