Research On Transmission Performance Of Broadband Microwave Multilayer Printed Circuit

The application and demand of System In a Package is increasing as the demand of high integration density and miniaturization of electronic equipment.The circuit based on LTCC as well as on Multilayer PCB play an important role in System In a Package.There are some inferiorities in LTCC circuit,such as high cost,limited purchase of key materials,and the problem of processing compatibility.For this reason,microwave printed circuit is widely used.At the same time,the design precision must be increased,because the multilayer printed circuit cannot debug the increasing of integration density.This paper mainly studies the typical structures of microwave multilayer printed circuit,such as Microstrip,Stripline,Coplanar waveguide and so on.Base on theoretical analysis,we get the thickness of dielectric,the width of line and some other technology index will influence signal transmission.According technology tolerance analysis using HFSS simulation,and some typical circuit to test,we get some useful conclusions as followings.The Microstrip transmission performance changes with the thickness of dielectric.For the Microstrip which dielectric thickness is 0.127 mm,transmission loss is 0.25dB/10mm@18GHz.For the stripline which dielectric thickness is 0.508 mm,transmission loss is 0.4dB/50mm@12GHz.Finally,we analyze a 3.5GHz~4.5GHz multilayer microwave filter,and get that the 0.127 mm dielectric thickness will reduce 13?m after manufactory.The pass band will move 150 MHz when the dielectric thickness changes 10?m.These conclusions may provide a good reference for tolerance design and problem analysis.