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Systems designed by humans have no "intelligence" and only execute algorithms; however, they may, somehow, mimic an intelligent behaviour (smart systems). Since, at present, information management in the electrical energy domain is extremely advantageous, smart systems require, all together, sensors, actuators, and electronic interfaces. In literature there is some confusion, and even some contradiction, between the parameters used for characterizing the properties of sensors and of electronic interfaces. In the first part of the paper we provide a unified, coherent set of definitions which may be applied to both sensors and electronic interfaces. Afterwards we show how non-electrical systems may be conveniently analysed in the electrical domain by means of equivalent circuits, and we review some techniques for the design of high performance electronic interfaces; finally, we show a few examples, which illustrate the use of those techniques in practical applications. © 2006 Elsevier B.V. All rights reserved

Renewable energy is a wide topic in environmental engineering and management science. Photovoltaic (PV) power has had great interest and growth in recent years. The energy produced by the PV system is intermittent and it depends on the weather conditions, presenting lower levels of production than other renewable resources (RESs). The economic feasibility of PV systems is linked typically to the share of self-consumption in a developed market and consequently, energy storage system (ESS) can be a solution to increase this share. This paper proposes an economic feasibility of residential lead-acid ESS combined with PV panels and the assumptions at which these systems become economically viable. The profitability analysis is conducted on the base of the Discounted Cash Flow (DCF) method and the index used is Net Present Value (NPV). The analysis evaluates several scenarios concerning a 3-kW plant located in a residential building in a PV developed market (Italy). It is determined by combinations of the following critical variables: levels of insolation, electricity purchase prices, electricity sales prices, investment costs of PV systems, specific tax deduction of PV systems, size of batteries, investment costs of ESS, lifetime of a battery, increases of self-consumption following the adoption of an ESS, and subsidies of ESS. Results show that the increase of the share of self-consumption is the main critical variable and consequently, the break-even point (BEP) analysis defines the case-studies in which the profitability is verified.

SummaryIn this paper, an implementation of a simulated grounded inductor (SGI) based on a recently developed active building block called second‐generation voltage conveyor (VCII) is proposed. The proposed SGI employs two VCIIs, two resistors, and one grounded capacitor, which is preferred when integration is involved. More importantly, unlike most of the other previously reported SGIs, this one is free from any restrictive matching conditions. A complete analysis of nonidealities along with sensitivity treatment by considering parasitic impedances and nonideal gains of the VCII are performed. A simple VCII circuit is designed to be used in the implementation of the proposed SGI. To support the presented theory, Pspice simulation results using 0.18‐μm CMOS technology parameters and supply voltage of ±0.9 V are provided. On the basis of the achieved results, the proposed SGI operates in a good agreement with an ideal inductor. The power consumption is only 0.65 mW, and the parasitic series impedance is approximately 191.9 Ω. The applicability of the proposed SGI is tested by using it in a standard second‐order high‐pass RLC filter.

A new current mode building block named voltage and current gain second generation current conveyor (VCG-CCII) is introduced. The voltage and current buffers of the standard CCII are replaced by voltage and current amplifiers with tunable gains so to obtain an extremely flexible and versatile building block. The VCG-CCII can be used in place of the standard CCII in impedance conversion applications so to utilize only one active component. A circuit implementation in a standard 0.35 lm CMOS process is presented and used to multiply, as an example, a 10 pF capacitor by a factor tunable from 1 up to about 3100, achieving a capacitance multiplication for more than 6 decades frequency range (from 0.15 to 865 KHz for the highest multiplication factor).

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In this paper, an active inductor (AI) with high linearity and high dynamic range, including a minimum number of components, is presented. The AI is composed by a single transistor, and by a passive compensation network; the latter allows the control of the values of both the inductance and the series resistance.In order to show the feasibility of the proposed AI for filter applications, a prototype board on a TLX8 substrate with a first-order active band-pass filter has been fabricated and tested. The filter has a center frequency of 2470 MHz (useful for Bluetooth applications) and a measured noise figure (NF) of 9 dB with a À5 dBm P 1 dB compression point, and a 75 dB dynamic range.By considering the filter NF, bandwidth and the P 1 dB, compression point, the dynamic range of the filter from noise floor (À174 dBm/Hz) to P 1 dB compression point is approx. 75 dB. The power consumption is approx. 5 mW. Linear and nonlinear analysis and measurements have shown an unconditionally stable filter response. A table resuming the aforementioned performance is given (see Table I) showing also comparisons with the state of the art. For all these reasons, the natural application of the proposed filter is as a post-selector in radio communications systems, after the low noise amplifier, or as a channel selector in the receiver IF chain. Moreover, it can be used for RF or microwave band selection application, as wakeup radio systems [29], where high dynamic range and selectivity are required without stringent noise performance. CONCLUSIONSWe have proposed a high-Q, high-linearity, and high dynamic range AI, requiring a minimum number of components. A high quality factor band-pass filter including the AI has been designed as a demonstrator. A prototype board on a TLX8 substrate has been fabricated and tested in order to show the AI feasibility for RF and microwave applications. The filter has a center frequency of 2470 MHz, in the Bluetooth frequency range, a measured NF of 9 dB, and a À5 dBm P 1 dB compression point. The resulting 75 dB dynamic range confirms the theoretical predictions and simulation results. The proposed AI, if properly designed, is unconditionally stable in the whole frequency range and can be used in practical applications. We remark that this aspect is usually underestimated in the literature, and, to our best knowledge, only few works give information about AI stability, power handling, and noise. SINGLE TRANSISTOR ACTIVE INDUCTOR 285

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