MODIFIED DOHERTY POWER AMPLIFIER FOR WIDER BAND

Wireless communication system are developing rapidly, due to which new standards like WIMAX and 4G Long Term Evaluating(LTE) with a purpose of achieving high data rate result in high end applications such as high speed internet, video conferences and broadband width. These applications require mobile base stations at the transmitter as well as at receiver (T/R) to support features like multiple bands, multiple modes, higher BW and less power consumption. The design and implementation of multi-standard transceivers for wireless mobile system is very complex task. In this paper we discuss the design of a wider band Doherty Amplifier, which operational frequency of 3 GHz to 3.75 GHz. The development of proposed DPA is based on techniques of inserting wider band compensators along with second and third harmonic tuning at the output of the GaN HEMT main and peak amplifier. In this work, the basic constraints in the basic DPA is ?/4 impendence transformer has been eliminated with the help of Branch Line Coupler (BLC). The designed amplifier gives the drain efficiency 70% - 75% at about 46-43 dBm output power and gain around 12 dB in the desired band.