Research On New High Performance BST Phase-shifters

Barium Strontium Titanate (BST) has been recognized as a kind of ideal material for phase shifters. Phase shifter using BST thin films is attracting more and more attention by it's advantages of low-cost, fast-response, wide-frequency band, small-size and easy to control, and it will greatly push the research on powered phased array radar in high frequency forward, which has a tight connection with national defense. At present, America and some European developed countries have obtained a series of progress in every region already. But after deeper research we can see that there're some disadvantages in every type of BST phase shifters. It needs more work to do still. Our country started later than the developed countries in this region, and we must be more creative in order to chase up with them based on the research nowadays.This thesis was funded by the Shanghai science committee (No.047252038) and the 973 item (No.2001CB610401).Firstly, the thesis reviewed the study status on BST phase shifters and the achievements abroad, and decided to research the distributed phase shifters using optimized interdigitated capacitors.In this paper, a new phase shifter which can achieve large phase-shift and low insertion loss has been proposed based on the theory of the distributed phase shifter's design model and the consideration of manufacturing cost. And this new design has been verified by ADS and HFSS simulating. 390° phase shift and less than 0.5dB loss have been obtained. Now a new patent (No.CN200510028313. 9) has been in the process of applying and already open to the public.In addition, two types of BST phase shifters using EBG have been researched. One model using EBG ground plane shows a good performance of 250° phase shift. Another type of ring resonance circuit doesn't have the same good results and needs to be improved.