Research On L-Band Gan Internally Matched Power Amplifier Design Technology

Power amplifiers are usually located in the radio frequency front-end transmitters and responsible for amplifying the input signal to high power level for antenna radiation,which are crucial for the system performance.Because of the performance defects of traditional semiconductor materials,microwave power amplifier output power is limited.The third generation of semiconductor devices GaN HEMTs have great potential for realizing microwave solid-state amplifiers,due to their characteristics for wide bandgap materials such as high breakdown voltage,high electron saturation velocity and high operating temperature.With the development of communication and radar systems,the requirements for small-size and high-power solid-state amplifiers have increasingly improved.The internally matched amplifiers are not only smaller and lighter than the external matched amplifiers,but also easier and cost less than the MMIC amplifiers.While the GaN HEMT internally matched amplifiers are applied to the high-power phased array radars,the small size and high power output improve the remote capability.Because the package areas of internally matched amplifiers are limited and the complex structures are difficult to integrate,especially under the condition of lower frequency range and wideband application.Therefore,the design of L-band internally matched power amplifiers is being studied in this dissertation.The main works are as follows:Because Power amplifier operating frequency band reached an octave,the broadband matching technology theory is used to achieve the broadband impedance matching.Compared with the traditional broadband structures,the multi-level low-Q low-pass LC matching network with smaller size is selected.Adopting the amplifier with two tubes takes one signal path to implement impedance matching in the structure forms for the small package.The power combination and synthesis are used to balance the phase and amplitude between the tubes.The formula derivation of single-stage LC matching network parameter is applied to the three-stage LC matching network combined with the low-Q broadband method.The impedance of the center frequency is matched,the formula is accurate and effective that is verified by the ADS circuit simulation.Calculation formulas are used to convert the lumped parameters into the distribution parameters.The source and load impedance matching is achieved multi-frequency broadband matching simulation within 1-2GHz.In the end,an L-band GaN internally matched amplifier has been fabricated in a package of 14.5mm*14.5mm.With the domestic GaN HEMTs,the capacitors are achieved by MIM and the inductors are achieved by high-impedance transmission lines in matching networks,bondwires are used to connect.At the bias point of VGS =-2.8V,VDS =28V,the measured result shows that,within 1~2 GHz,this amplifier that operates in continuous wave(CW)mode achieves a small signal gain over 10.5dB and input power Pin= 37 dBm,output power Pout> 45 dBm,drain efficiency ?D> 44% at 85? and 25?;output power Pout> 47 dBm,drain efficiency ?D> 52% at-55?.The matching structures used in this dissertation can be integrated in a smaller package than the traditional one that uses the T-type network for pre-match and the coupler or Wilkinson power divider for two-way synthesis.The research has practical significance in realizing the broadband matching under the internally matched structures of GaN power.