Patent ID: 6181208
Filing Date: 2001-01-30
Classification: H03F,H03G

Abstract:
A switchable path power amplifier suitable for amplifying an input signal received at a power amplifier input in order to generate an output signal at a power amplifier output the switchable path power amplifier comprising:a first power device including a first power device input coupled to the power amplifier input and a first power device output, the first power device suitable for amplifying the input signal the first power device intended for use during a first operating state of the switchable path power amplifier;a second power device including a second power device input coupled to the power amplifier input and a second power device output, the second power device suitable for amplifying the input signal, the second power device intended for use during a second operating state of the switchable path power amplifier;a combining network device including a first combining network device input coupled to the first power device output, a second combining network device input coupled to the second power device output, and a combining network device output coupled to the power amplifier output, the combining network device being operable to select between the first power device and the second power device such that only one of the first power device and the second power device drives the power amplifier output; anda state determination circuitry operable to determine the operating state of the switchable path power amplifier, wherein the state determination circuitry is arranged to control which power device drives the power amplifier output based upon the state of the switchable path power amplifier, and wherein the state determination circuitry enables the first power device and disables the second power device when the switchable path power amplifier is operating in the first state, and wherein the state determination circuitry enables the second power device and disables the first power device when the switchable path power amplifier is operating in the second state, and wherein the combining network device selects the enabled power device as the power device that drives the power amplifier output, and wherein the combining network device includes:an inductor L1 having first and second terminals, the first inductor L1 terminal electrically coupled to the first power device output;a capacitor C1 having first and second terminals;an inductor L2 having first and second terminals, the first inductor L2 terminal being coupled to a common ground reference, and the second inductor L2 terminal, the second inductor L1 terminal, and the first capacitor C1 terminal being coupled together;a transmission line having first and second terminals, the first transmission line terminal, the second capacitor Cl terminal, and the power amplifier output being coupled together;a capacitor C2 having first and second terminals, the second capacitor terminal C2 being coupled to the common ground reference;a capacitor C3 having first and second terminals, the first capacitor C3 terminal, the first capacitor C2 terminal, and the second transmission line terminal being coupled together;an inductor L3 having first and second terminals, the first inductor L3 terminal being coupled to the common ground reference; andan inductor L4 having first and second terminals, the first inductor L4 terminal being coupled to the second power device output, the second inductor L4 terminal, the second inductor L3 terminal, and the second capacitor C2 terminal being coupled together.