| The 3rd generation mobile communication system needs good network framework so that it can support lots of operation. Especially anywhere and anytime, it can provide private communication operation for anybody. In the network layout, the trunk amplifier and repeater are cheaper than base station. For the signal coverage in the weak and blind places, they are better than base station because of their less bulk. The trunk amplifier and repeater are very important for optimizing network. As the key part of the trunk amplifier and repeater, power amplifier plays an important role in these systems.The major task of the paper is to design a 10W linear power amplifier module based on improving signal coverage range of the WCDMA downlink. The operation frequency range is from 2110MHz to 2170MHz. Based on the analytical method of nonlinearity distortion and the whole course of design, simulation, debugging, test etc for power amplifier, work of five aspects is chiefly carried out as follows:1. Theoretically the profound analysis is made for the behavior model of amplifier, and the analytical method for distortion of amplifier is introduced in detail.2. Based on the difficulty of designing linear power amplifier because of high peak-average-power-ratio of WCDMA signal, the primary parameters on linearity of power amplifier such as EVM are analyzed.3. The circuit for detecting power level is used in the output port of power amplifier. The automatic level control circuit keeps steady output power level in the output port of trunk amplifier or repeater.4. The design, optimizing and simulation for power amplifier is done by the simulation software. Finally, the power module which is satisfactory for the lineafity of trunk amplifier or repeater systems is made by debugging and testing.5. A kind of scheme about predistortion PA is presented. The scheme has its rationality and some disadvantages. |
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