Rf Front-end Engineering Study Based On The Structure Of The Double-sided Parallel Strip Line (dspsl)

The balanced technology has been of increasing attraction to microwave circuits and antenna design due to its high suppression to environmental noise, as well as excellent EMC performance. The microstrip line (MSL) or coplanar waveguide (CPW) is applied in the conventional balanced technology, which usually requires the baluns to be the transition between the unbalanced and the balanced circuits so that much space would be occupied, in addition, the extra loss will be introduced. Furthermore, the differential signal will be affected because of the frequency dependence of the baluns, the application in wideband systems is thus not possible.The problem above can be solved by the double-sided parallel strip line (DSPSL). DSPSL is one kind of balanced transmission lines, in which the RF signal inherently takes the features of equal amplitude and frequency-independent out-of-phase between two identical strips. DSPSL can thus find wide applications in differential/balanced circuitry construction.This paper will study the features of DSPSL as detailed as possible. The RF front-end module, such as power divider, antenna, and bandpass filter will be designed on the platform of DSPSL.The main works in this thesis are listed below:1) Analyzing the performances of DSPSL. The emphases are focused on how to realize high characteristic impedance and introduce the way to design a transition between DSPSL and other planar transmission lines. At the same time, the effect on circuitry of a ground plane inserted in DSPSL will be discussed, too.2) A planar dipole and 2×2 parallel-fed dipole array are designed utilizing the balanced-fed feature of DSPSL to achieve wider bandwidth, the experimental verification has also been carried out to demonstrate the validity of the design strategies. In addition, a log-periodic dipole antenna is designed to meet the demand of UWB application.3) A compact dual-mode DSPSL bandpass filter is designed. A novel resonator is adopted to excite dual-mode, and then fractal theory is used to achieve more compact geometry. The defected ground structure (DGS) is also applied to improve insertion loss and wide stopband. Furthermore, a planar dipole element is designed and integrated with this bandpass filter, the potential for DSPSL's IC can thus be validated simply.The purpose of this paper is to study the potential applications of DSPSL in the RF front-end, which is expected to lay foundation for the further engineering application.