| Whether in wireless communication systems, satellite navigation systems, or militaryradar and electronic warfare systems, RF power amplifier is one of the core components, itoccupies many important key technologies and up to about30%of the equipment cost of asystem. Therefore, a study on the power amplifier is significant. Broadband, high linearityand high efficiency power amplifier is the focus of future research and development, due toCDMA system uses varying envelope digital modulation techniques, making the systemlinearity requirements more stringent.The project is under the demand of low cost and high linearity power amplifier ofrepeater in CDMA system, and the goal of this paper is to design a linear power amplifierwith working frequency in865~880MHz, rated output power is16W, and linearity is thefocus of the design.Compared to the small-signal amplifier, power amplifier works in alarge-signal state, so the design would be much more difficult.The paper first introduces the significance of power amplifier design and itsdevelopment state. Chapter two describes the basic theoretical foundation of the RF poweramplifier design requires, including common classification, operating characteristics andcommon technical indicators of the power amplifier, the bias circuit and the matchingcircuit of the power amplifier is been made theoretical analysis and design methodssummary. Chapter three gives the design process of power amplifier, including thequiescent operation point selection and bias circuit design, stability analysis, optimum loadand source impedance pull simulation and the corresponding matching circuit design. Thenthe small-signal S-parameter and large-signal nonlinear simulation is made, finally thePCB territory is been designed. Chapter four describes the RF index test of the amplifier.The test results show that the gain is20.66dB when the output power reaches up to16W, the ripple is0.84dB, the VSWR is lower than1.3, the IMD3is-49.18dBc, the HMD2,HMD3are-59.52dBc and-81.59dBc. |
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