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This paper presents bulk acoustic wave resonators using the ferroelectric materials barium titanate and barium strontium titanate. The electric field induced piezoelectric effect in these materials is utilized in the design of various types of intrinsically switchable bulk acoustic wave resonators. Both thickness mode and lateral mode resonator results, which have been demonstrated recently, are summarized in this paper. Significantly improved quality factors by means of forming a ferroelectric-on-silicon structure are also demonstrated.

A novel compact dual-band bandpass filter (DBPF) using SIRs with open-stub line and 0-degree feed structure is presented in this paper. The low-band is obtained by using hairpin type Stepped Impedance Resonators (SIR) split ring through electrical coupling, And by tuning a pair of open-stub lines the high-band is realized too. In order to improve the stop band attenuation, zero-degree feed structure is implemented to introduce three transmission zeros. So the proposed DBPF has high selectivity, and is also simple in design and compact in structure. Finally the proposed filter is designed and fabricated, and the simulation and test results are in good agreement.

In this paper an experimental X-band radar system, called DTU-VISDAM, developed for the detection and monitoring of human vital signs is described. The DTU-VISDAM radar exploits a low intermediate frequency (IF) heterodyne RF front-end architecture and single-sideband (SSB) transmission for easier and more reliable extraction of the vital signs. The hardware implementation of the proposed low-IF RF front-end architecture and associated IF circuitry is discussed. Furthermore, the signal processing and calibration steps necessary to extract the vital signs information measured on a human subject are described.