APPARATUS FOR IMPROVING PERFORMANCE AT LOW POWER REGION IN A DOHERTY AMPLIFIER

摘要

A method and apparatus improve the performance of a carrier amplifier in a Doherty amplifier. The Doherty amplifier includes a power divider, a carrier amplifier, at least one peaking amplifier, offset lines, and a Doherty circuit. The power divider provides a power signal to each of the carrier amplifier and the at least one peaking amplifier. The carrier amplifier amplifies power of a signal inputted from the power divider. The at least one peaking amplifier amplifies power of a signal inputted from the power divider. The offset lines control a load impedance when the at least one peaking amplifier does not operate. When the at least one peaking amplifier does not operate, the Doherty circuit generates the load impedance of the carrier amplifier that is larger than twice a load impedance at the maximum output power of the carrier amplifier.