| Radio Frequency(RF)amplifier is applied to many fields and RF generator is one of them.RF amplifier is mainly researched on the paper.The amplifier is a key module of RF generator and its performance directly influences the whole system performance.Its design requirements are different from amplifiers of other fields,so it always is a difficult point of designing RF generator to realize high power,high efficiency,excellent linearity,less harmonics and less spurious wave.It is researched for application of RF amplifier on a RF generator to increase amplifier's efficiency,suppress noise and harmonic wave,and optimize filter structure.A new amplifier pattern is proposed.Filter is moved from after the second stage to before the second stage on the pattern.The pattern that noise is filtered after being amplified is changed into that noise is filtered before being amplified.The new pattern rapidly improves amplifier's efficiency.A resonance filter is designed.The filter is realized via making use of performance of LC series circuit and LC parallel circuit.Impedance of the former is very small at resonance point and big at non-resonance point.Performance of the latter is the opposite.Circuit combination permit RF signal pass and noise is transmitted to electric ground.A transformer of Three-Transmission Line is designed.The transformer connected to both input port and output port of power amplifier can restrain harmonic wave and noise,and transform impedance.Push-pull amplifier is redesigned as power amplifier.Both biasing network and DC conditioning circuit are modified.Instrument transformer is connected to gate and source terminals of MOSFET.The transformer can contribute to getting high gain.Matching network also is designed by Smith circle tool.The circuit of 13.56 MHz amplifier is designed and simulated by Advanced Design System(ADS).The circuit of 27.12 MHz amplifier also is designed.The amplifier is built and tested,and system performance meets requirements. |
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