Research And Design Of Dielectric Delay Microwave Circuit

Since American scientist H.N.yquistand S.Brand proposed the "group delay" conce pt in 1930s,the researchers from all over the world developed an interest in this filed ,and began the in-depth research.Especially after entering the new century,with the t heory development of space exploration、satellite navigation、communication rada、mi llimeter wave measuring and continuous improvement of the level of software and har dware, requirements of the transmission capacity and channel transmission characteristi cs of communication system are also becoming more and more demanding.Through th eory and practice, found that the phase in the process of signal transmission can carry a greater amount of information, the stability is higher.Then group delay is used to i ndicate phase linearity of the important parameters,Thus more and more researchers b egin to start a research group delay.Especially in recent years, because of its special p erformance and application in the field of feedforward amplifiers and antenna array, et c,attracted the attention of researchers all over the world, and had certain research res ults, has become a hot research topic.However, at present the research achievements of negative group delay circuit mainly concentrated in the western developed countries, particularly in the United States and Japan, domestic for the research of this field is s till in its infancy,according to the author knows, the current domestic haven’t specializ ed books and literature to discuss the negative group delay circuit theory and design, in this paper, the part of the circuit structures in domestic are still belongs to the first time.This article in view of the present domestic textbooks for the group delay conce pt explanation is not clear, combining with foreign negative group delay related theory, using the resonant circuit characteristic, to the principle of generating negative group delay the rigorous mathematical and explanation on the physical plane.And then use th e results of the above analysis,combined with the need of modern communication syst em,designed four different negative group delay circuits,which consist of a composite negative group delay circuit、a distributed transmission line negative grope delay circui t、a coupled lines negative group delay circuit and a multisection asymmetrical coupler negative group delay circuit,all of circuits’center frequency are 2.2GHz. These four n egative group delay can get the maximum negative troup delay respectively are-5.8n s、-6.8ns、-9ns and-3.5ns, and the largest negative group delay bandwidth can be achi eved respectively 92MHz、104Mz、120MHz and 400MHz,and have low singnal atten uation.In this paper,the above each kind circuit working principle has carried on the d etailed analysis,and using the ADS2009 to the simulation,to verify the rationality and correctness of the circuit design,and gives the advantages and disdvantage of each kin d of circuit structure and the improvement direction.Through summarizing the characteristics of the above four types of negative gro up delay circuits,and combined the characteristics of band-stop filters,propose a new de sign thought of negative group delay circuit.Through that approach,design a new grou p delay circuit which center frequency is 2.2GHz, the maximum negative troup delay is-6.8ns, and negative group delay bandwidth could be got 120MHz.All of results ha ve been through landscape simulation verify its correctness.At the end of this paper,t o the circuit stages and the relationship between the negative group delay circuit perfo rmance for detailed analysis,its laid a good ground work for future design work.