Thin-film phase shifter for micro-wave filter network and preparation

Abstract

The invention discloses a thin-film phase shifter of a microwave filter network and a manufacturing method, wherein the phase shifter is formed by a substrate, a ferroelectric thin film, a surface electrode and a base electrode and has a multi-layer structure of a microwave filter network, and the microwave filter network is formed by a changeable distribution parameter portion and a non-changeable distribution parameter portion, wherein the changeable distribution parameter portion of the microwave filter network is formed on the ferroelectric thin film, and the non-changeable distribution parameter portion of the microwave filter network is formed on the substrate. The thin-film phase shifter achieves microwave phase shift through changing distributed capacitance parameter values in networks. In addition, the ferroelectric thin film which is chosen by the thin-film phase shifter is a barium titanate zirconate thin film. And therefore, the invention has the advantages of stable performance, excellent impedance matching, low loss, simple circuit topology, easy achieving technique, small size and light weight.

Description

technical field [0001] The invention relates to a thin-film phase shifter, in particular to a microwave low-pass filter network ferroelectric thin-film phase shifter used in the wireless communication field and a preparation method thereof. Background technique [0002] Phased array antennas are the mainstream in the development of modern radar and wireless communications. Both in the military and in the civilian communication system, it has fully demonstrated its advantages, and has become the focus of competing research in various countries. The electronically controlled digital phase shifter is the core component of the phased array antenna in the field of phased array radar, satellite communication and mobile communication. The electronically controlled digital phase shifter is the core component of the phased array antenna in the fields of phased array radar, satellite communication, and mobile communication. It has fully demonstrated its advantages in both military an...

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Problems solved by technology

The phase shift conversion time is slow, even on the order of milliseconds, which seriously affects the modulation speed of the signal and the electronic scanning speed of the radar beam in the application, and can only be made in the waveguide, and cannot be used in the planar circuit

(3) The digital phase shifter of potassium arsenide monolithic microwave integrated circuit (MMIC) also has the inherent defect of excessive insertion loss, and can only be produced on the potassium arsenide production line, and the cost is high

Common electrode materials include gold and high-temperature superconducting oxides, among which gold electrodes are more commonly used; in terms of materials, gold is a good conductor, but if there is no good adhesion and sufficient thickness, the gold electrode itself will bring damage to the device. Large loss, the usual problems are: the thickness of the gold electrode is not enough, the electrode design is unreasonable, resulting in a mismatch with the circuit impedance

[0013] (1) The input and output circuits are not simulated and optimized together in the microwave circuit topology model. The above-mentioned ferroelectric film phase shifter also needs to consider the matching problem of the input and output microwave circuits. In this way, it is difficult to obtain the best impedance matching, and the circuit topology The structure is more complex and the process is difficult to realize

[0014] (2) Both the invariant part and the variable part of the microwave low-pass filter network are constructed on the structure of strontium barium titanate (Ba 1-x Sr x TiO 3 Abbreviated as BST) ferroelectric film, unable to reduce the mismatch and small insertion loss requirements in the microwave low-pass filter network system

[0015] (3) Although barium strontium titanate has good adjustable dielectric properties; its disadvantage is that the dielectric loss is relatively large, and this loss comes from two aspects: on the one hand, it is the intrinsic reason, namely Titanium itself has two valence states of +3 and +4, and it is difficult to ensure that all titanium ions are in the valence state of +4 in the thin film; and the change between these two valence states leads to an increase in material loss, and another On the one hand, the film preparation process may also cause increased loss

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