V. Palazzari

A New Contactless Assembly Method for Paper Substrate Antennas and UHF RFID Chips

This paper deals with a low-cost method for the assembly of flexible substrate antennas and UHF RF identification silicon (Si) chips. Such a method exploits a magnetic coupling mechanism, thus not requiring for galvanic contacts between the Si chip and antenna itself. The magnetic coupling is established by a planar transformer, the primary and secondary windings of which are implemented on flexible substrate and Si chip, respectively. As a result, the Si chip can be assembled on the antenna with a mere placing and gluing process. First, the idea has been validated by theory. Electromagnetic simulations of a square heterogeneous transformer (1.0-mm side) show a maximum available power gain (MAG) of -0.4 dB at 868 MHz. In addition, the heterogeneous transformer is also quite tolerant with respect to misalignment between primary and secondary. An offset error of 150 μm reduces the MAG to - 0.5 dB. A sub-optimal matching strategy, exploiting a simple on-chip capacitor, is then developed for antennas with 50- Ω input impedances. Finally, the idea has been experimentally validated exploiting printed circuit board (PCB) prototypes. A PCB transformer (1.5-mm side) and a transformer rectifier (two-diode Dickson multiplier) have been fabricated and tested. Measurements indicates a MAG of -0.3 dB at 868 MHz for the transformer and the capability of the developed rectifier to supply a 220-kΩ load at 1.5 V with a - 2-dBm input power.

A cost driven 24 GHz Doppler radar sensor development for automotive applications

This paper deals with a low-cost 24 GHz Doppler radar sensor for traffic surveillance. The basic building blocks of the transmit/receive chain, namely the antennas, the balanced power amplifier (PA), the dielectric resonator oscillator (DRO), the low noise amplifier (LNA) and the down conversion diode mixer will be presented underlining the key technologies and manufacturing approaches by means the required performances can be attained while keeping industrial costs extremely lowThis paper deals with a low-cost 24GHz Doppler radar sensor for traffic surveillance. The basic building blocks of the transmit/receive chain, namely the antennas, the balanced power amplifier (PA), the dielectric resonator oscillator (DRO), the low noise amplifier (LNA) and the down conversion diode mixer are presented underlining the key technologies and manufacturing approaches by means the required performances can be attained while keeping industrial costs extremely low.

IF Amplifier Section in 90 nm CMOS Technology for SoC Microwave Radiometers

In this letter a novel design solution in 90 nm CMOS technology is proposed for the IF amplifier, low-pass filter and square-law power detector of a system-on-chip (SoC) microwave radiometer. To minimize the number of off-chip components (just a single capacitor) the IF filter is based on an active gmC configuration, whereas the power detector exploits the MOS transistor non-linearity, i.e., avoiding the need for Schottky diodes. The fabricated IF chip features a sensitivity of 3 mV/nW, a linearity range of about 25 dB around the -60 dBm level, a noise equivalent bandwidth of 58 MHz and a current consumption of only 1.8 mA at 1.2 V supply. The core area is within a rectangle of 220 mum times 540 mum. The proposed design solution is also compatible with SiGe BiCMOS processes and can be regarded as a further step toward the realization of microwave radiometric sensors fully integrated on silicon.

Development of Low-Cost 24-GHz Circuits Exploiting System-in-Package (SiP) Approach and Commercial PCB Technology

This paper deals with 24-GHz circuits developed by exploiting a system-in-package approach. In order to reduce the cost as much as possible, a standard multilayer printed circuit board (PCB) technology has been adopted. Such a circuit consists of a package built utilizing a 0.3-mm thick fiber-glass substrate with 3.38 relative permittivity. The contacts between the substrate and the mother board are realized along the package perimeter exploiting 0.6-mm via-hole metalization and half halo shield soldering pad. First, the developed package is simulated and optimized by means of commercial electromagnetic software. Then a prototype is fabricated and measured. The obtained results show that the whole frequency band from DC to 30 GHz can be covered. A packaged 26.5-mm straight microstrip line exhibits an |S11| value better than -12 dB and an |S21| value of about -1.4 dB at 24 GHz. This value is only 0.6-dB worse than that of the unpackaged line. A single-balanced diode mixer and a low-noise amplifier (LNA) for industrial, scientific, and medical applications are then designed. The integration of these building blocks within the PCB package is finally demonstrated and experimentally verified. The packaged mixer shows a 6.8-dB conversion loss. The packaged LNA, instead, features a 9.1-dB gain with a 3.4-dB noise figure.

Crossed dipole frequency doubling RFID TAG based on paper substrate and ink-jet printing technology

A frequency doubler TAG structure realized on both plastic and conductive ink-jet printed paper is presented. It is based on the crossed dipole structure, but uses four diodes in a bridge configuration to form a balanced multiplier layout and incorporates the necessary DC path in a simple way within the structure. Measurements results are presented for both the plastic and paper structure, showing the feasibility of economic and green electronics on paper.

Low-cost assembly of UHF RFID chips and flexible substrate antennas by magnetic coupling approach

This article deals with a novel low-cost technology for the assembly of flexible substrate antennas and UHF RFID Si chips. Such a technology exploits a magnetic coupling mechanism, thus avoiding the need for galvanic contacts between the Si chip and the antenna itself. The magnetic coupling is established by a planar transformer, whose primary and secondary windings are implemented on flexible substrate and Si chip respectively. As a result the Si chip can be assembled on the antenna with a mere placing and gluing process. First the idea has been validated by theory. Electromagnetic simulations of a square heterogeneous transformer (1.0 mm side) show a minimum loss of 0.6 dB at 900 MHz, under simultaneous matching conditions. Then a symmetrical PCB transformer (1.5 mm side) has been fabricated and tested. Measurements indicates a minimum loss of 0.3 dB at 900 MHz, thus confirming the validity of the proposed solution.

Development of a Low-Cost Microwave Radiometer for the Early Detection of Fire in Forest Environments

This paper deals with the development of a microwave, noise-adding radiometer, purposely designed for the fire detection in forest environments. The sensor operates at 12.65GHz and exploits commercial TV-SAT components such as a parabolic dish and a low-noise down-converter. First, an electromagnetic model is presented in order to estimate the radiometric contrast (increase of the brightness temperature with respect to the background) due to a fire covered by vegetation. Then, the design of the sensor is addressed, underlining the key technologies that allow the required performances to be attained at low industrial costs

A low-cost 24GHz doppler radar sensor for traffic monitoring implemented in standard discrete-component technology

This paper deals with both the implementation and the real-life characterization of a low-cost 24GHz Doppler radar sensor, purposely designed for the traffic monitoring. To reduce industrial costs as much as possible a discrete-components technology has been adopted for the microwave front-end. Plastic packaged devices and fiberglass reinforced substrate are used in such a way as to fit with standard PCB manufacturing processes and automated assembly procedures. The signal manipulation is based on a state-machine algorithm and has been implemented in a 8051 family micro-controller unit. The realized sensor has a typical output power of 6dBm and mounts a planar antenna with a 3dB beam-width of plusmn4.5 degrees. The real-life measured performances shows a detection range in excess of 300 meters.

An active cuber circuit for power amplifier analog predistortion

This work deals with an active balanced cuber-circuit that can be used as IM3 generator in analog predistortion systems for mean power amplifiers. Such a circuit exploits the odd non-linear characteristic of a B-class push-pull amplifier and, compared with conventional diode designs, shows an improved third-order generation. A laboratory prototype of the cuber has been realized and inserted in a predistortion system and, as a next step, a pre-industrialized predistorter prototype has been realized using the active-cuber block: the whole system seems to be flexible enough to be used for the IM3 linearization of PAs. From experimental results obtained from a target 6W power amplifier we found that more than 8 dB of correction can be achieved in a fractional bandwidth of about 10%.

Leaf compatible “eco-friendly” temperature sensor clip for high density monitoring wireless networks

This paper describes the design, realization and application of a custom temperature sensor devoted to the monitoring of the temperature differential between the leaf and the air. This difference is strictly related to the plant water stress and can be used as an input information for an intelligent and flexible irrigation system. A wireless temperature sensor network can be thought as a Decision Support System (DSS) used to start irrigation when effectively needed by the cultivation, thus saving water, pump fuel oil and preventing plant illness caused by over-watering.