Self-testing solution are very useful not only for make sure that devices are operating in the correct way, but also to realize system auto-calibration: auto-calibration is based on the experimentally extraction of proper parameters and it is usually realized by adopting radio frequency noise injection subsystems. In these cases, the systems use power acquisition devices, based on diode detectors, to perform the measurements; this solution denotes poor reconfigurability, unless a very complicated system architecture is adopted. In this paper we prove that the measurements needed for the over mentioned purpose, can be performed avoiding the application of complex architectures, by using software-defined radios with high level of potential reconfigurability and flexibility.

Avalanche noise diodes have recently been demonstrated in standard Si technologies such as CMOS and SiGe BiCMOS processes and used to design fully integrated noise sources. This letter investigates the reproducibility (die-to-die and run-to-run) and the stability over time of these devices. On-wafer noise sources are indeed relevant because of their extensive use in mm-wave noise measurements and for the calibration of high performance, single-chip receivers and radiometers. The results, obtained for the case study 30-GHz noise sources in 130-nm SiGe BiCMOS technology, show that a 0.3-dB reproducibility is achieved (ten dice fabricated in three different foundry runs) and that the generated noise has a stability of 0.07% in a period of 1000 min (Allan deviation of fractional temperature fluctuations). This will enable a new class of built-in test equipment (BITE) for terrestrial and space applications.

This paper presents a passive wireless harmonic transponder capable of transmitting information acquired by its vibration sensor. The system is equipped with a Schottky diode frequency doubler which converts the received signal from f ₀ to its second harmonic 2 f ₀. The sensed information is then encoded in the 2 f ₀ carrier phase using a varactor phase-shifter (acting as the phase modulator) biased through a piezoelectric transducer (which senses the mechanical vibrations). The transponder operation is demonstrated with particular focus on piezoelectric transducer vibrating resonance frequency. The side-band amplitude of the backscattered signal increases by about 10 dB for an increment of the acceleration of the mechanical system under test of 1.5 g 128 Hz.

This paper investigates, for the first time, the feasibility of harmonic tag sensors based on orthogonally polarized waves. The main tag building blocks (circular and dual polarization antennas, Schottky diode frequency doubler and phase shifter) are designed, implemented with standard PCBs technology and materials, and experimentally characterized. Finally a proof-of-concept of the whole system operating at 1.04/2.08 GHz is proposed and validated in laboratory. The system can recover the encoded phase regardless the interrogation distance.

This contribution demonstrates, for the first time, on-chip Built-In Self Test (BIST) circuits based on avalanche noise diodes, a class of devices that are recently developed up to millimeter-waves in commercial Si technologies. The proposed BIST is constituted by a Low-Noise Amplifier (LNA) integrated with an avalanche p-i-n diode. The LNA has two equal channels that can be enabled independently. The first channel is connected to the input pads and, when active, the circuit operates as a standard LNA. The second channel, instead, is tied to the noise diode through a coupling capacitor and a 6-dB resistive attenuator. If the second channel is selected, the LNA works in self-test mode. As a consequence, the LNA gain and noise figure can be determined by switching on and off the integrated noise source and measuring the output noise power in these two conditions. The fabricated LNA (14.4-dB gain and 3.8-dB noise figure) is based on a 130-nm SiGe BiCMOS technology and operates between 20 and 30 GHz, i.e., in a frequency band compatible with 5G services. The integrated noise source (avalanche p-i-n diode with attenuator) has an Excess Noise Ratio (ENR) of about 17 dB at 30 GHz when biased with a 4 mA current. Experiments shows that measurements from the input pads (LNA mode) agree with those using the internal noise source (BIST mode) within 0.7 dB for gain and 1.3 dB for noise figure.

This paper presents a passive wireless vibration sensor capable to transmit the information related to both vibration frequency and amplitude. These information are encoded in the interrogation carrier phase using a varactor phase-shifter (acting as the phase modulator) directly connected to a piezoelectric transducer (which senses the mechanical vibrations). The phase shifter consists of a 90-degree hybrid junction in which the direct and coupled ports are closed on identical reactive impedances: a voltage-controlled variable capacitance (varactor diode) and a fixed inductor. The sensor is intended to be part of a passive wireless harmonic transponder able to retrieve the sensor information from the re-transmitted modulated signal. The sensor demonstrated to sense vibration up to 400 Hz with a 2 g peak acceleration. For the re-transmitted signal, the sidebands amplitude increases of about 10 dB as the acceleration of the mechanical system under test varies between 0.5-2.0 g at 100 Hz.

The era of Internet-of-Things is leading to the widespread of sensors in medical and consumer applications, where electronics is aiming at being wireless, battery-less, lowcost and wearable. In this context, pressure sensors are of particular interest since they can be used to monitor parameters such as human posture, motion and interaction with the environment. This paper presents a novel zero-power pressure sensor with wireless communication and wireless powering feature, with a flexible sensing element. The key component of the sensor is a Schottky-diode harmonic transponder connected to a piezoresistive transducer. The piezoresistor is placed along the DC path of the rectifier circuit in order to control the rectifying behaviour of the diode and thereby encoding the information about pressure on the backscattered signal. This sensor is a proof of concept of a novel fully-passive and wireless pressure sensor with a flexible sensing element.

This contribution describes the feasibility of a wireless sensor that uses Micro-Electro-Mechanical Systems (MEMS) on cellulose materials. In particular, the focus is on a paper-aluminum (paper-Al) bimorph cantilever formed by an Al foil glued on top of a paper layer. It is well known that paper relaxes its fibers in the presence of humidity. This means that the length of the paper layer increases (respect to the Al layer) when humidity is absorbed, thus determining the cantilever deflection. Such a mechanism is used to control a capacitor formed by the cantilever itself (Al layer) and by a metal plate printed on a PCB. The capacitor is then applied to a planar notch filter whose resonant frequency is hence determined by the humidity. The preliminary experiments show that the developed circuit features a 2.45 GHz center frequency and a sensitivity of about 3.7 MHz ner each nercent of relative humidity variation.

This paper proposes a Ka-band receiver front-end for future CubeSats Low-Earth Orbit (LEO) to Geostationary (GEO) inter-satellite links. The receiver is able to support very high data rates (up to 100 Mbit/s) in Quadrature Phase-Shift Keying (QPSK) when in the line of sight of a GEO satellite that is equipped with a steerable 70-cm antenna and transmitting a 25-W signal. The originality of the proposed approach is twofold. First we will demonstrate the receiver feasibility based on a class of miniaturized and low-cost microwave integrated circuits, currently available on the market. In particular, our receiver is based on a novel combination of integrated Low-Noise Amplifiers (LNA) with an image rejection filter, the latter exploiting the Substrate Integrated Waveguide (SIW) technology. An optimization of the via placement proved to be able to reduce the need for shielding apparatuses, thus simplifying the mechanics and reducing mass, volume and hardware costs. Secondly, we will propose a noise injection circuit capable of measuring and calibrating the receiver gain, also during in-orbit operation. Self testing capabilities are particularly relevant for CubeSats because the usage of commercial components poses serious reliability issues.