PV Cell Characteristic Extraction to Verify Power Transfer Efficiency in Indoor Harvesting System

A method is proposed to verify the efficiency of low-power harvesting systems based on Photovoltaic (PV) cells for indoor applications and a Fractional Open-Circuit Voltage (FOCV) technique to track the Maximum Power Point (MPP). It relies on an algorithm to reconstruct the PV cell Power versus Voltage (P-V) characteristic measuring the open circuit voltage and the voltage/current operating point but not the short-circuit current as required by state-of-the-art algorithms. This way the characteristic is reconstructed starting from the two values corresponding to standard operation modes of dc-dc converters implementing the FOCV Maximum Power Point Tracking (MPPT) technique. The method is applied to a prototype system: an external board is connected between the transducer and the dc-dc converter to measure the open circuit voltage and the voltage/current operating values. Experimental comparisons between the reconstructed and the measured P-V characteristics validate the reconstruction algorithm. Experimental results show the method is able to clearly identify the error between the transducer operating point and the one corresponding to the maximum power transfer, whilst also suggesting corrective action on the programmable factor of the FOCV technique. The proposed technique therefore provides a possible way of estimating MPPT efficiency without sampling the full P-V characteristic

A gated oscillator clock and data recovery circuit for nanowatt wake-up and data receivers

This article presents a data-startable baseband logic featuring a gated oscillator clock and data recovery (GO-CDR) circuit for nanowatt wake-up and data receivers (WuRxs). At each data transition, the phase misalignment between the data coming from the analog front-end (AFE) and the clock is cleared by the GO-CDR circuit, thus allowing the reception of long data streams. Any free-running frequency mismatch between the GO and the bitrate does not limit the number of receivable bits, but only the maximum number of equal consecutive bits (Nm). To overcome this limitation, the proposed system includes a frequency calibration circuit, which reduces the frequency mismatch to ±0.5%, thus enabling the WuRx to be used with different encoding techniques up to Nm = 100. A full WuRx prototype, including an always-on clockless AFE operating in subthreshold, was fabricated with STMicroelectronics 90 nm BCD technology. The WuRx is supplied with 0.6 V, and the power consumption, excluding the calibration circuit, is 12.8 nW during the rest state and 17 nW at a 1 kbps data rate. With a 1 kbps On-Off Keying (OOK) modulated input and −35 dBm of input RF power after the input matching network (IMN), a 10^(−3) missed detection rate with a 0 bit error tolerance is measured, transmitting 63 bit packets with the Nm ranging from 1 to 63. The total sensitivity, including the estimated IMN gain at 100 MHz and 433 MHz, is −59.8 dBm and −52.3 dBm, respectively. In comparison with an ideal CDR, the degradation of the sensitivity due to the GO-CDR is 1.25 dBm. False alarm rate measurements lasting 24 h revealed zero overall false wake-ups

A broadband current sensor based on the X-Hall architecture

A broadband current sensor, which is fully integrated and galvanically-isolated, is presented in this paper. The current sensor relies only on a Hall-effect probe to realize the magnetic sensing core so as to minimize the cost and the occupied space. Bandwidth limitations of state-of-the-art Hall-effect probes are overcame by combining the novel X-Hall architecture with a wide bandwidth differential-difference current-feedback amplifier. A prototype implemented in 0.16 \u3bcm BCD technology demonstrates a bandwidth wider than 20 MHz. Offset, sensitivity and power consumption are comparable to the state of the art. This is the first Hall-only current sensor achieving a bandwidth higher than 3 MHz

What's in a Sign? Trademark Law and Economic Theory

Abstract: The aim of this paper is to summarise the extant theory as it relates to the economics of trademark, and to give some suggestions for further research with reference to distinct streams of literature. The proposed line of study inevitably looks at the complex relationship between signs and economics. Trademark is a sign introduced to remedy a market failure. It facilitates purchase decisions by indicating the provenance of the goods, so that consumers can identify specific quality attributes deriving from their own, or others', past experience. Trademark holders, on their part, have an incentive to invest in quality because they will be able to reap the benefits in terms of reputation. In other words, trademark law becomes an economic device which, opportunely designed, can produce incentives for maximising market efficiency. This role must, of course, be recognised, as a vast body of literature has done, with its many positive economic consequences. Nevertheless, trademark appears to have additional economic effects that should be properly recognized: it can determine the promotion of market power and the emergence of rent-seeking behaviours. It gives birth to an idiosyncratic economics of signs where very strong protection tends to be assured, even though the welfare effects are as yet poorly understood. In this domain much remains to be done and the challenge to researchers is open

On road tire deformation measurement system using a capacitive-resistive sensor

This paper presents a novel approach to continuously measure the mechanical deformations of a tire due to contact with asphalt, by embedding capacitive–resistive sensors in it. A strain monitoring method is proposed, which adopts the tire itself as a sensing element. In this way, the sensing area is pushed towards the tread interface (the part of the tire in direct contact with the asphalt), where the information concerning tire state is actually generated. Tire deformation causes a change of the spacing between the steel wires inside the tire carcass and this change is translated into an impedance change of that region of the tire. By measuring such an impedance change, our approach makes it possible to determine the deformation of the tire. Static stress–strain measurements show a linearity of about 80% in the impedance–strain relation. A linear impulse of tensile strain has been used to validate the detection of instantaneous changes in the tread–asphalt interface. The mechanical solicitation resulted in a 1% deformation of the specimen’s main dimension. Experimental results report a change of about 40% in the real part of the impedance and a change of about 20% in the imaginary part of the impedance. The same measurements have been performed varying the temperature within a range of −20 to 90 ◦C, which is compatible with the operating conditions of a commercial car tire

Active Probe card for electrical wafer sort of integrated circuits

L'oggetto del brevetto \ue8 un circuito e un metodo per collaudare in modalit\ue0 non a contatto circuiti e dispositivi integrati su fetta di silicio

Method for verifying the alignment between electronic devices

A method for verifying alignment between two integrated circuits connected to form a 3D stack. The method is based on a reference communication channel and several adjacent channels: the difference in the received signals allows to detect misalignments in x,y and z direction