High-Linearity 60W Doherty Amplifier for 1.8GHz W-CDMA

In this paper, we describe the design of a 60-W Doherty amplifier at a frequency band of 1.8 GHz. The 60-W Doherty amplifier is composed of two 190-W continuous wave (CW) output power laterally diffused metal-oxide semiconductor (LDMOS) devices. To improve the linearity and efficiency of the 60-W Doherty amplifiers, the impedance matching circuits of the carrier amplifier and peaking amplifier were optimized using a high-frequency circuit design simulator and a system simulator. Experimental results using one-carrier wide-band code division multiple access (W-CDMA) signals achieved a 33% drain efficiency and a -36 dBc adjacent channel leakage power ratio (ACLR) at a 5-MHz offset in the frequency band range of 1844.9 MHz to 1879.9 MHz. The electrical performance for two-carrier W-CDMA signals was also measured. This is a report on the highest power of a Doherty amplifier at a frequency band of 1.8 GHz to the best of the authors´ knowledge