Optimum Reflection-Type Phase Shifter Using (Ba,Sr)TiO₃ Thin Film

Authors: Kim Y-T.¹; Ryu H-C.²; Kwak M-H.²; Moon S-E.²; Lee S-J.²; Kim S-H.¹; Park J-S.³; Han S-K.⁴

Source: Integrated Ferroelectrics, Volume 56, Number 1, Volume 56/2003 , pp. 1107-1114(8)

Publisher: Taylor and Francis Ltd

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Abstract:

In this paper, in order to obtain a large differential phase shift with a little change in applied voltage, a ferroelectric reflective load circuit has been designed on top of barium strontium titanate (Ba,Sr)TiO₃ [BST] thin film. The design of the ferroelectric reflection-type phase shifter is based on a reflection theory of terminating circuit, which has a reflection-type analogue phase shifter with two ports terminated in symmetric phase-controllable reflective networks. To achieve large amounts of phase shift in low bias-voltage range, the effects of change of capacitance and transmission line connected with two coupled ports of a 3-dB 90° branch-line hybrid coupler have been investigated. A large phase shift with a small capacitance change in the parallel terminating circuit has been demonstrated in the paper.

Keywords: Reflection-type phase shifter; ferroelectric reflective circuit; (Ba, Sr) TiO3 thin films; BST interdigital capacitor

Document Type: Research article

Affiliations: 1: Division of Information Technology Engineering, Soonchunhyang University 2: Basic Research Laboratory, Electronics and Telecommunications 3: School of Electric Engineering, Kookmin University 4: RF-tron Co. Ltd