Design And Research Of Small High Performance Multiplexers Based On LTCC

With the rapid development of wireless communications and intelligent technology,our life has changed a lot.Both military equipment such as radar spacecraft,space exploration,airborne and shipboard equipment,individual equipment etc.and various civil electronic products such as smart phones,personal computer,medical equipment,wearable devices etc.have the development trend of miniaturization and high performance.So that the multiplexer which can share the transmitting channels and receiving channels is attracting more and more attention and research.With the help of LTCC(Low Temperature Co-fired Ceramic)technology which has excellent three-dimensional space characteristics,this paper carried out deep exploration and research into the realization of multiplexer with miniaturization and high performance.The main works and contributions are concluded as following:(1)The first band-pass diplexer is left-right structure and both channel band-pass filters are set up with lumped elements.In order for steeper sidebands and higher stop-band rejection,transmission zeros are added by additional capacitance.The three-dimensional models of band-pass filters are placed in left-right structure and the public port gets rematch by inductance-capacitance circuit.After many times of optimization,the simulation model of band-pass diplexer can be sent to production.Ultimately,the measured curve is good enough for the electricity function index and its size is only 10mm*10mm*2.35mm.(2)The second band-pass diplexer is up-down structure and both channel filters are set up with semi-lumped elements.Magnetic coupling is used to connect adjacent resonator cells and Z-shape cross coupling capacitance is adopted to add transmission zeros.The three-dimensional models of band-pass filters are placed in up-down structure and the public port gets rematch by inductance-capacitance circuit.After many times of optimization,the simulation model of band-pass diplexer can be sent to production.Ultimately,the measured curve is good enough for the electricity function index and its size is only 3.2mm*5.5mma*2.35mm.(3)The third band-pass diplexer is wingspan structure and both channel filters are set up with distributed elements.Transmission zeros are added by Z-shape cross coupling capacitance.The three-dimensional models of band-pass filters are placed in wingspan structure and the public port gets rematch by 1/4 wave length network.After many times of optimization,the simulation model of band-pass diplexer can be sent to production.Ultimately,the measured curve is good enough for the electricity function index and its size is only 2mm*7mm*1.5mm.(4)Finally,three products can all meet the established electrical performance index and their volume is very small at the same time.More daringly,we can speculate the similar approach to build multiplexer and that guess is proved by software simulation.The successful attempt opens up a new train of thought for subsequent multiplexer and even the whole system to realize the miniaturization and high performance.