Development Of A High-linearity Wideband Uultra-shortwave Transmiter

The rapid development of wireless communication technology, increasing theindicators requirements of the communication system, high-power, wideband and highlinearity have become three major issues which need to address by communicationsequipment. Depth analysis and research have been made on the three issues respectively,signal transmission system of high-power broadband and high linear has been designed.On the side of systems, analyzed the gain and power distribution of poweramplifier, determined to achieve high gain amplifier of signal by three cascadedamplifier, the program of improve the power amplifier output linear by the using offrequency-selective components has proposed, analyze the problem of selectedfrequency group pieces linear, design a PIN series-parallel structure RF switch, toachieve high linear output of the system.Analyzed the principle of LC match and the matching technology of coaxialtransmission line transformer, compared the effect of two matching technology in RFbroadband by simulation and experiment, simulated effects of push-pull impedancetransformation of the transmission line transformer, and using4:1and9:1push-pullimpedance transformation technology to match the last stage power amplifier.Analyzed the system cooling of high power output, compared the temperaturedistribution of FR4, ceramic, copper three materials in the high power, by COMSOLsimulation software ’s thermal field simulation of power transistor,decided the thermaldesign of power amplifier chip and PIN diode,to achieve the high-power signal outputof the system.Researched the law of impact on RF switch output harmonic suppression of PINdiode forward conduction current, reverse the cut-off voltage, the number of parallelbranch, Eritrea flow inductance frequency characteristics curve and PIN diode circuitconnection, designed the High Line sexually selected frequency components, achievedthe high linear output of the system.Achieved the signal transmission system with high-power broadband and highlinearity, which meeting the circuit indicators of system.