Patent ID: 8717099

Claim:
A wideband Doherty amplifier circuit, comprising: a main amplifier configured to operate in a linear mode; a peaking amplifier configured to operate in a non-linear mode; and a Doherty combiner directly connected to an output of each amplifier so that no output match devices are in the path between the amplifier outputs and the Doherty combiner, the Doherty combiner configured to present the same load impedance to each amplifier when both amplifiers are amplifying and present a modulated load impedance to the main amplifier when the peaking amplifier is not amplifying so that the variation in a voltage standing wave ratio (VSWR) seen by the main amplifier is less than 5% over a plurality of frequency bands, wherein the main amplifier has an optimal output impedance Z 1 and size T 1 , the peaking amplifier has an optimal output impedance Z 2 and size T 2 , the Doherty combiner comprises a transmission line having an impedance Z 3 directly connected to the output of the main amplifier at one end and directly connected to the output of the peaking amplifier at an opposing end, and Z ⁢ ⁢ 3 = ( Z ⁢ ⁢ 1 × Z ⁢ ⁢ 2 × T ⁢ ⁢ 2 T ⁢ ⁢ 1 ) 1 2 .