Lumped Element Branch-line Coupler Based On LTCC Process

With the rapid development of the communication field,the upcoming 5G wave has been ushered in from 2G in just ten years.People have higher demand for communication,which has forced the industrial chain of materials,technology related to it to be further improved.Among them,the miniaturization,broadband and high performance of the communication system are in the first place,and it is an urgent need to solve and constantly need to update the iteration.At present,with the deepening of research on microwave device materials,technologies and processes at home and abroad,the three-dimensional layout process design based on Low Temperature Co-fired Ceramic(LTCC)is unanimously recognized.The LTCC can be imaged as a multi-layer PCB stacked together,connecting the upper and lower layers through vias,and compatible with other wiring technologies,making full use of internal space to integrate passive components.The three-dimensional space and the assembly density are increased,and the volume of the RF device is effectively reduced,thereby achieving high integration.Moreover,the LTCC substrate has better heat conduction characteristics than the widely used PCB substrate,improving the reliability of the circuit;In addition,the low sintering temperature of the LTCC can co-fire the excellent conductor materials,such as Cu,Ag,etc.,improving electrical conductivity and promoting high performance.The branch-line coupler proposed in this thesis uses the lumped parameter ?-type network transmission line for equivalent,which realizes the miniaturization of circuit size and volume.The center frequencies of the branch-line coupler designed in this thesis are 2.5 GHz and 4.7 GHz,respectively.For the branch-line coupler with a center frequency of 2.5 GHz,three LTCC models are designed and simulated according to the degree of coupling.The coupling degrees are 10 dB,15dB and 20 dB respectively to verify that lumped parameter ?-type network transmission line realizes the rationality of the theory of volume miniaturization;For the branch-line coupler with a center frequency of 4.7 GHz,three models are designed.The order of the multi-order branch is first-order,second-order and third-order,respectively,to verify the improvement of the broadband.Finally,the circuit simulation results,electromagnetic simulation results and test results of the designed lumped parameter divider are compared,and the measured results are in good agreement with the simulation results.The theory and conjecture of the miniaturization and wideband are verified.