High efficiency feed-forward amplifier using RF predistortion linearizer and the modified Doherty amplifier

The prototype model of the high efficiency feed-forward amplifier using RF predistortion linearizer and the modified Doherty amplifier is developed, and the performance of the developed amplifier is examined experimentally. The efficiency of 13.6% with the output power of 45W is achieved under the condition that ACLR (Adjacent Channel Leakage Power Ratio) is -55 dBc in 3 GPP test method at room temperature of +25/spl deg/C. This is the top level performance among the previously reported feed-forward amplifiers for cellular base stations. In concerning with the modified Doherty amplifier, which is the key component to enhance the efficiency of feed-forward amplifier, the design method and its performance is described in detail.