The Research And Design Of RF Power Amplifier

RF-PA can be applied in a variety of wireless transceiver modules, including such hand-held terminal equipment as cell phones, intercom and radio. It is the core component of those wireless transceiver modules. It is required that RF-PA should be equipped with certain transmit power and efficiency, good stability, low noise and safety of use when it is in practical application. The thesis designs the two-stage low noise power amplifier based on ADS simulation software which can be applied to the frequency band, ranging from 400MHz to 470MHz. This RF amplifier can realize more than 23dB gain, absolute stability condition with stability coefficient greater than 1 and low noise condition with noise figure less than 1. It can restrain the second harmonic, third harmonic and high frequency clutter of amplified master frequency by externally connecting resonant filter circuit. The whole system includes input matching network, bias network, power amplifier circuit, output matching circuit and resonant filter circuit. Power tube in the RF-PA system makes use of transistor FHX05LG from Fujitsu Company, with the merits of low noise, high electron mobility and high gain of single tube. It can also become multistage power amplifier through the cascade so as to further enhance the gain, thus requirements of the design can be met. Single-stage power of FHX05LG transistor can be amplified to achieve the gain of more than 12dB. To complete the design, this thesis takes advantage of the two-stage FHX05LG transistor cascade to realize the amplification of RF power. Smith chart is adopted to analyze the configuration and parameters of matching network. After combining with ADS software simulation, specific parameters of the circuit are determined.This paper first introduces fundamental theories and technical parameters of the RF-PA and gets the specific configuration and technical parameter of single-stage power amplifier circuit after the theoretical analysis and calculation. Then ADS simulation and Smith chart are employed to determine whether the technical indicators meet the requirements of the design. Finally it comes to accomplish the design. By externally connecting antenna and controlling circuit by voltage, the RF power amplifier is able to realize the emission of RF.