| In radio communication system,due to the frequency selectivity of RF devices itself and the cascading of multiple components,the system doesn't have an ideal amplitude and phase characteristic,which mainly performance at the uneven amplitude characteristics and fluctuating group delay characteristic.That makes the transmission signal distortion,and ultimately affect the communication quality and transmission speed of the system.It's one of the most direct and effective compensation method to add an analog broadband amplitude equalizer or phase equalizer at the transmitter front-end,taking the volume,power consumption and complexity into considerations,the analog passive equalizer which can suitable for high speed communication attached attentions from researchers.The value of equalization has been developed from a few dB to more than a dozen dB,and its bandwidth is expanded from MHz to GHz,while an equalizer with simple structure,easy to debug,low power consumption,small size,ultra wide band and suitable for high frequency still needs to be studied and researched furtherly.In this paper,we mainly study the analog passive wideband amplitude equalizer and phase equalizer.Based on the research of traditional lumped element equalizer,the resistor loading microstrip resonant stub and suspended stripline equivalent replacing lumped element are used to achieve an amplitude equalizer with the advantages of simple structure,small size and ultra-broadband;in view of phase equalizer,starting from the two order X type allpass network,by analyzing its group delay characteristics,several practical T type equalizer network are derived and the design and implementation of wideband phase equalizer are reached in this dissertation.According to the difference of frequency band and structure,three kinds of design methods are used,which are lumped parameter structure,microstrip structure and suspended stripline structure,and five different types of amplitude equalizer and three different types of phase equalizer are designed eventually.The main contents of this paper are as follows:1)The research background,the development status on the domestic and foreign,and the classification are introduced,and the importance and necessity of the equalizer in the communication system are discussed also.2)We studied the amplitude and phase characteristics of the RF devices,and its effect on the system performance;the network analysis methods the equalizers are introduced in this paper.At the same time,a simple summary of the lumped parameter network,microstrip transmission line theory and suspended sripline theory are presented,and based on these theories,this thesis discuss the basic characteristics and equivalent circuit of microstrip resonance stubs,as well as the physical structure and the calculation formula of capacitance's and inductance's value for suspended sripline.3)Design of analog wideband amplitude and phase equalizer.Firstly,starting from the RC parallel network and LC resonance branch,kinds of lumped parameter common structure equalizer is introduced in the article;on the basis of a microstrip transmission line and suspended stripline's equivalent lumped circuit,we use microstrip stub replace the LC resonant branch to derive a microstrip equalizer,and substitute the capacitor and inductor with suspended sripline to deduce a linear suspended sripline equalizer;secondly,according to equalizer analysis method,this dissertation finds the solution of various equalizer structures' transfer function,and investigates the influencing factors for equalizer's bandwidth,equalization value,delay fluctuation and so on;then,equalizer simulation circuit and 3D structure electromagnetic emulation model are built with ADS or HFSS,to analysis its circuit characteristics,and debugging and optimization;what's more,we do the hardware implementation,drawing electrical schematic and printed circuit board(PCB)by CADENCE.After manufacture and process,welding,debugging,testing and results analyzing on the PCB physical circuit are done. |
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