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The extremely high permittivity of ferroelectric varactors (typically ϵr > 100) imposes specific design and fabrication constraints for microwave and millimeter-wave applications. In this paper, small-size parallel-plate ferroelectric varactors insensitive to fabrication misalignment tolerances are studied experimentally. It is shown that the total resistance of the varactors strongly depends on the shape factor of the plates. Moreover, due to the small sizes of the varactors, the interconnecting strips become narrow and their contribution to the total resistance dominates. A simple procedure for optimization of the shape factor to minimize the varactor resistance is proposed.

Oscillators based on AlN thin-film bulk acoustic resonators are designed, fabricated and measured. The circuits are realised as silicon-on-silicon multichip modules where SiGe transistors are flip-chip mounted on a novel carrier substrate which includes monolithically integrated resonators and passive components. The paper describes the development and processing of the carrier substrate and resonators, as well as the development of the oscillator circuits.

This paper reports a K-band voltage-controlled oscillator based on room-temperature ferroelectric varactors. The circuit is realized as a hybrid module where flip-chip transistors are mounted on a silicon substrate with integrated ferroelectric varactors and passive circuitry. The size of the module is 4.7times2.2 mm2. The measured center frequency is 16.5 GHz with a linear tunability of 6.7% and an output power of 3 dBmplusmn1 dB over the tuning range. The measured phase noise at center frequency is -95 dBc/Hz at 100-kHz offset. Another version of the oscillator is measured operating at 19.6 GHz with a tunability of 3.3% and a phase noise of -102 dBc/Hz at 100-kHz offset

Integration possibilities of Ba x Sr 1-x TiO 3 (BST) based tunable Thin Film Bulk Acoustic Wave Resonators (TFBAR) using all-dielectric SiO 2 /AlN Bragg reflectors deposited on a high resistivity silicon strate are considered. SiO 2 /AlN reflectors withstand the high deposition temperature (≫600C) of the BST films opening up possibilities for heterogeneous integration of complex microwave circuits.

A model and a robust extraction procedure for tunable thin-film bulk acoustic resonators (TFBARs) are proposed. The TFBARs are based on induced piezoelectricity in Ba x Sr 1−x TiO 3 films. Their tunable characteristics as represented by the extracted model parameters are interpreted and discussed.

A 2 GHz oscillator based on a solidly mounted AlN Thin-Film Bulk Acoustic Resonator (TFBAR) is reported. The oscillator is realised as a silicon-on-silicon Multi-Chip Module (MCM) where all passive elements, including the TFBAR, are monolithically integrated on a High-Resistivity Silicon (HRS) carrier. SiGe transistors are flipchip mounted on the MCM carrier. Measurements of the oscillators reveal a best phase-noise of −125 dBc/Hz at 100 kHz offset.

This paper describes low-frequency measurements and comparative analysis of methods used for surface passivation of high-resistivity silicon (HR-Si). A number of substrates are evaluated; n-type and p-type HR-Si, with and without surface passivation by means of polysilicon or Ar-ion implantation. Additionally, a selection of samples is prepared with a layer of ferroelectric material. Substrate characteristics are extracted from measurements of the samples, allowing comparison of passivation methods and evaluation of the influence of the ferroelectric film. The study shows all passivation methods successful in removing any bias-dependence of substrate properties. Further, the high-temperature processing of the ferroelectric film is observed increasing the extracted substrate conductivity by about 70% for the Ar-ion implanted samples, and about 50% for the p-type samples passivated by poly-Si. The effective substrate conductivity of the n-type samples passivated by RTA-crystallised poly-Si appears unaffected.

Coplanar waveguides (CPWs) on surface passivated highly resistive Si (HRS) covered by ferroelectric film are studied. The focus is on passivation techniques reducing losses caused by surface charge accumulation at the Si/SiO2 interface. Different passivation methods are considered, Ar-ion bombardment into the silicon substrate and deposition of poly-Si below the oxide layer. Both methods remove any bias-dependence and decrease the losses associated with surface charge accumulation. It is also concluded that the effect of passivation remains after pulsed laser deposition of a ferroelectric thin film.

This paper reports the circuit model of a SiGe HBT transistor flip chipped onto a high-resistivity silicon carrier (substrate). It includes the parasitic capacitances and inductances associated with bumps, the flipped transistor chip and takes into account the effect of the high-permittivity ferroelectric film deposited on the silicon carrier.

This paper describes the design and measurement of a 2 GHz oscillator based on a Solidly Mounted Thin Film Bulk Acoustic wave Resonator (SM TFBAR). The circuitry is patterned on an alumina substrate on which the transistors and capacitors are soldered. The SM TFBAR chip is integrated by means of wirebonding. The measured oscillator centre frequency is about 2.038 GHz with an output power of 0 dBm.

Parallel-plate capacitors based on ferroelectric thin films are considered as high density capacitors and varactors. Due to the small thickness of the ferroelectric films, typically less than 1.0 mu m, high electric fields are generated even at relatively low voltages inducing piezoelectric effect associated with electrostriction. This induced piezoelectric effect has negative impact on ferroelectric capacitors since it causes extra loss (electroacoustic transformation of microwave energy). In this work the use of Bragg reflectors between the substrate and ferroelectric film is proposed as a possible way of suppression of the enhanced losses associated with the piezoelectric activity of the ferroelectric film.

Field and temperature dependent parameters of the dc field induced resonances in BaxSr1-xTiO3-based tunable thin film bulk acoustic resonators