Alessandro Cazzorla

A 5.6-GHz UWB Position Measurement System

This paper describes the design and realization of a 5.6-GHz ultrawide-bandwidth-based position measurement system. The system was entirely made using off-the-shelf components and achieves centimeter-level accuracy in an indoor environment. It is based on asynchronous modulated pulse round-trip time measurements. Both system level and realization details are described along with experimental results including estimates of measurement uncertainties.

Low Complexity UWB Radios for Precise Wireless Sensor Network Synchronization

Wireless sensor networks are becoming widely diffused because of the flexibility and scalability they offer. However, distributed measurements are significant only if the readout is coupled to time information. For this reason, network-wide time synchronization is the main concern. The objective of this paper is to exploit a very simple hardware implementation of an IR-UWB radio for realizing an accurate synchronization system for wireless sensors. The proposed solution relies on commercial-off-the-shelf discrete electronic components (rather than on specialized transceivers). It is designed for providing accurate timestamping of the packet time of arrival (TOA) to an adder-based tunable clock, which tracks the network time reference. The comprehensive set of experimental results based on prototypes, shows a TOA detection error with a standard deviation well below 1 ns. On the other hand, in the FPGA-based prototype, the synchronization performance reaches an overall synchronization error of few nanoseconds. Finally, in order to highlight the tradeoff between timestamping accuracy, clock stability, and synchronization performance, some additional simulations have been carried out: a synchronization error in the order of 1 ns is possible, if good local oscillator sources are available in the nodes and if the adjustable clock has a sufficient resolution.

High-precision UWB-based timestamping

The work presented in this paper is related with time synchronization for wireless networks. In particular, it is focused on the proposal and experimental evaluation of a low-cost and high precision timestamping technique based on Ultra Wide Band (UWB) signalling. In recent years, the use of such systems has gained an increasing success thanks to their robustness to interferers and multipath. In this paper a new hybrid wireless node is proposed; a traditional IEEE802.15.4 radio, the reference physical layer for wireless sensor networks, is supported by an UWB transceiver. The former is used for communication purposes and allows to preserve compatibility with already installed infrastructures/networks; the latter is used for time of arrival estimation. Hardware prototypes have been realized and experimental tests have shown a sub-nanosecond accuracy. A comparison with commercial solutions has shown a performance improvement with respect to conventional approaches.

MEMS-based LC tank with extended tuning range for low phase-noise VCO

This paper presents the modeling, manufacturing, and testing of a micro-electromechanical system (MEMS)-based LC tank resonator suitable for low phase-noise voltage-controlled oscillators (VCOs). The device is based on a variable MEMS varactor in series with an inductive coplanar waveguide line. Two additional parallel stubs controlled by two ohmic MEMS switches have been introduced in order to increase the resonator tunability. The device was fabricated using the FBK-irst MEMS process on high resistivity (HR) silicon substrate. Samples were manufactured with and without a 0-level quartz cap. The radio frequency characterization of the devices without 0-level cap has shown a continuous tuning range of 11.7% and a quality factor in the range of 33–38. The repeatability was also tested on four samples and the continuous tuning is 11.7 ± 2%. Experimental results on the device with a 0-level cap, show a frequency downshift of about 200 MHz and a degradation of the quality factor of about 20%. This is, most likely, due to the polymeric sealing ring as well as to a contamination of the ohmic contacts introduced by the capping procedure. A preliminary design of a MEMS-based VCO was performed using Advanced Design System and a hardwired prototype was fabricated on Surface Mount Technology on RO4350 laminate. The prototype was tested resulting in a resonance frequency of 5 GHz with a phase noise of −105 and −126 dBc at 100 KHz and 1 MHz, respectively, and a measured output power of −1 dBm.

RF-MEMS Application to RF Tuneable Circuits

The bursting wireless communication market, including 5G, advanced satellite communication systems and COTM (Communication On The Move) terminals, require ever more sophisticated functions, from multi-band and multi-function operations to electronically steerable and reconfigurable antennas, pushing technological developments towards the use of tunable microwave components and circuits. Reconfigurability allows indeed for reduced complexity and cost of the apparatuses. In this context, RF MEMS (Micro-Electro-Mechanical-Systems) technology has emerged as a very attractive solution to realize both tunable devices (e.g. variable capacitors, inductors and micro-relays), as well as complex circuits (e.g. tunable filters, reconfigurable matching networks and reconfigurable beam forming networks for phased array antennas). High linearity, low loss and high miniaturization are the typical advantages of RF MEMS over conventional technologies. Micromechanical components fabricated via IC-compatible MEMS technologies and capable of low-loss filtering, switching and frequency generation allow for miniaturized wireless front-ends via higher levels of integration. In addition, the inherent high linearity of the MEMS switches enables carrier aggregations without introducing intermodulation distortions. This paper will review the recent advances in the development of the RF MEMS to RF tunable circuits and systems.

MEMS based LC tank with extended tuning range for Multi-band applications

This paper presents the modeling and simulations of compact multi-band MEMS based LC tank resonator suitable for very low phase-noise VCO. The resonator is based on a high-Q spiral inductor and high capacitive ratio varicap fully integrated in FBK-irst MEMS manufacturing process. Simulation results show that the resonator allows for an overall tuning range of 60% in the frequency range 2.15GHz-3.85GHz. Two separate regions of continuous tuning range (9.5% and 30%) allow to cover the whole frequency spectrum of WiMAX and IEEE802.11a/b/g/n. Theoretical quality factor (Q) is about 60 calculated as -3dB approach.

A novel Dual Gap MEMS varactor manufactured in a fully integrated BiCMOS-MEMS process

This paper presents the design and manufacturing of a novel Dual Gap MEMS varactor which operates before the pull-in ensuring continuous tuning range. The device is based on interdigitated DC and RF electrodes, allowing uniform distribution of the electrostatic force. The tunable capacitor has been embedded in the BEOL (Back End Of Line) metallization stack of a state of the art Si/SiGe BiCMOS semiconductor process allowing for easy integration with MMIC. Two different variants have been manufactured showing a maximum capacitive ratio of 2.12 and 4.46 respectively. By using mechanical stoppers, very stable down state capacitance values have been measured.

Woodchip humidity measurements using EM pulse propagation time

In this paper, a system for measuring moisture content of wood-chip samples is presented, based on propagation time measurements of electromagnetic pulses in a two wire probe. Both simulation and experimental results are reported, validated by concurrently performed TGA measurements. It is shown that the proposed approach may be advantageous, since it features a good sensitivity and a very high measurement speed.