Research On Key Technologies Of Ultra-small And High-performance Diplexer

With the rapid development of wireless communication technology,communication equipment and its derived communication services are constantly updated and iterated.The growing popularity of new technologies has brought broad market prospects,but also put forward more strict requirements for the design and production of electronic device.Low temperature co-fired ceramics(LTCC)is an important technology in multi-chip module(MCM)technology,which has the advantages of small size,light weight and easy integration.LTCC devices have a market share of about 6.5 billion,likely to exceed 10 billion in the next few years,with most of it dominated by the United States and Japan.Although domestic terminal manufacturers are stepping up the layout of LTCC market,but the current degree of localization is still not optimistic.A series of localization problems in the design and production of LTCC need to be solved in China.At present,there are few reports about LTCC diplexers,and the performance and size are too far removed from what foreign monopolies are selling.This thesis solves the three difficulties in the design of LTCC diplexer,and presents the finished diplexers in the form of different operating frequencies and different performance characteristics.The main research contents are as follows:The application range of the single π equivalent model of LTCC inductance and capacitance is demonstrated.The single π equivalent model is improved by combining the possible parasitic effect in the circuit and the empirical formula of inductance and capacitance.The precise coupling model of inductance and capacitance is formed,and the higher application frequency range and better fitting results are obtained,which proves the reliability of the model.The LTCC diplexer for WLAN dual frequency band(2.4GHz/5GHz)was designed.The low-pass part used the precise coupling model of inductance and capacitance to form a complete low-pass filter circuit.The number of transmission zeros in the simulation results of the three-dimensional model was verified,and the applicability of the precise coupling model in the whole circuit was further demonstrated.The realized LTCC diplexer is only 1.6mm×0.8mm×0.6mm and has the advantages of miniaturization,extremely low insertion loss,high isolation and high out of band suppression.The LTCC diplexer for GPS(1.575GHz)/ISM(2.4GHz/5GHz)band is designed.The filter circuit is designed and the element values are derived by using the low-pass prototype filter and transmission zero theory.The number of band-pass filter zeros is verified by the definition of Y matrix.Few diplexer designs can achieve the package size of 1608 in the same operating frequency band,while meeting the performance requirements of low insertion loss and high isolation.An LTCC diplexer for LTE dual band is designed.A reasonable circuit topology is used to realize the high rectangularity and out-of-band suppression of the low-pass filter.The out-of-band suppression of the band-pass filter is improved by the parasitic coupling effect of the element to generate extra transmission zeros.A miniaturized LTCC diplexer with high rectangularity and high out-of-band suppression at the second and even third harmonics is realized,with a size of only 2.0mm×1.2mm×0.6mm.