Patent ID: 7560983

Claim:
An amplifier circuit, comprising: a strong amplifier having an input node and an output node, said strong amplifier being most efficient over a first range of power; a weak amplifier coupled to said input node of said strong amplifier, said weak amplifier being most efficient over a second range of power and said second range of power being lower than said first range of power; an impedance transformation circuit coupled to said weak amplifier and to said output node of said strong amplifier, said impedance transformation circuit providing increased impedance to generate a higher potential at said output node of said strong amplifier and providing increased efficiency over said second range of power; a third weaker amplifier coupled to said input node of said strong amplifier, said third weaker amplifier being most efficient over a third range of power and said third range of power being lower than said second range of power; and a second weaker impedance transformation circuit coupled to said third weaker amplifier and to said output node of said strong amplifier, said second weaker impedance transformation circuit providing increased impedance to generate a higher potential at said output node of said strong amplifier and providing increased efficiency over said third range of power; and a control circuit biasing said strong amplifier to be activated when said first range of power is present and biasing said weak amplifier to be activated when said second range of power is present.