1,721,045 research outputs found
On the Introduction of Neural Network-based Optimization Algorithm in an Automated Calibration System
No full textThis work presents the introduction of a neural network-based optimization approach in the tuning of voltage-controlled circuits (such as active filters). A custom calibration system has been already presented by the same Authors. It was realized with a hardware interface and a dedicated software based on a modified version of a Differential Evolution algorithm. In this paper the implemented algorithms are described in detail together with a possible integration of the neural network synthesis to further enhance performance of the proposed system. As the first step in exploiting neural networks, in this paper they are used as a tool for speeding up the choice of initial values of the filter control voltages. Neural networks are used to replace a look-up table representing the relationship between filter parameters, the central frequency and the corresponding attenuation, and the control voltages. According to the obtained results, in such a way, the optimization time is shortened significantly
SPICE Model Identification Technique of a Cheap Thermoelectric Cell Applied to DC/DC Design with MPPT Algorithm for Low-Cost, Low-Power Energy Harvesting
No full textIn this work, an identification technique of a simple, measurements-based SPICE (Simulation Program with Integrated Circuit Emphasis) model is presented for small low-cost Peltier cells used in thermoelectric generator (TEG) mode for low-temperature differences. The collection of electric energy from thermal sources is an alternative solution of great interests to the problem of energy supply for low-power portable devices. However, materials with thermoelectric characteristics specifically designed for this purpose are generally expensive and therefore often not usable for low cost and low power applications. For these reasons, in this paper, we studied the possibility of exploiting small Peltier cells in TEG mode and a method to maximize the efficiency of these objects in energy conversion and storage since they are economical, easy to use, and available with different characteristics on the market. The identification of an accurate model is a key aspect for the design of the DC/DC converter, in order to guarantee maximum efficiency. For this purpose, the SPICE model has been validated and used in a design example of a DC/DC converter with maximum power point tracking (MPPT) algorithm with fractional open-circuit voltage. The results showed that it is possible to obtain a maximum power of 309 µW with a Peltier cell 2 × 2 cm at a ΔT of 16 °C and the designed SPICE DC/DC converter performance proved the improvement and optimization value given by the TEG model identification
GaAs Monolithic Wideband VCO for S and C bands
No full textThis work presents a GaAs monolithic voltage-controlled oscillator (VCO) for S and C bands. It has enhanced performance in term of both linearity and tunability, providing a wideband solution for modern re-configurable communication systems. The chip has been designed and fabricated with the HB20M technology process provided by UMS Foundry. Measurements show very good results demonstrating the feasibility of the proposed design strategy. The measured tuning range is about 30%; the VCO shows an average sensitivity of about 83 MHz/V with a minimum output power of 11.4 dBm and a phase noise lower of -107 dBc/Hz at 100 kHz of frequency offset from the carrier
Stability Characterizing Function for Electronic Circuit Design Based on Frequency-Domain Analysis With Parametric Damping
Full text linkA stability characterizing function (SCF) to be used for small and large-signal stability analysis and design of single and multitransistor electronic circuits is proposed. Stability constraints based on this function can be integrated with the framework of standard computer-aided design (CAD) procedures. The method is based on the bounded-input–bounded-output (BIBO) stability criterion, where a suitable set of input and output variables is chosen at the ports of all the nonlinear intrinsic electron device (IED) models. These variables are linked by a nonlinear state perturbation (NSP) matrix, whose elements are directly computed by analyzing an associated parametrically damped (PD) (i.e., stabilized) circuit. The proposed SCF is defined in terms of the NSP matrix elements and is a scalar function of frequency and the damping parameter. Circuit stability margins are easily evaluated by visual inspection of the plot of this function. Preliminary experiment validation is carried out by applying this approach for checking the self-starting capabilities of an oscillator as well as for the small and large-signal stability analysis of a two-transistor balanced amplifier and a single-transistor PA
A low-cost portable spherical directional anemometer for fixed points measurement
No full textWe present a novel anemometric system, which could be also suitable for IC integration with MEMS technology. The proposed approach is illustrated at both the design and implementation level, and it allows reliable absolute and relative wind measurement to be obtained for both fixed point or moving vehicles, for instance, on boats. The solution here represents a low-cost, low-power, portable measuring system. The prototype makes use of a fully 3D-printable spherical structure, that acts as an air conveyor, and a differential pressure measuring technique. A preliminary feasibility study has been conducted, strengthened by computational fluid dynamic simulations, and the following measurements on the prototype that has been fabricated have shown promising results. As a result, the test campaign on the prototype has allowed to obtain reliable performance on the wind speed measurement in the range 0–20 m/s and a directional measuring range of 306° with a precision of about ±2.5% and ±3.5% for the wind speed and wind angle, respectively
Enhancing performance of a InGaP/GaAs VCO by means of a switching architecture
No full textThe introduction of a compact switching architecture in the design of a monolithic microwave integrated voltage-controlled oscillator (VCO) is described, that is able to provide enhanced characteristics in term of both linearity and tunability. The proposed solution is applied to the design of a C-band GaAs MMIC (monolithic microwave integrated circuit) VCO. The chip has been realised with the heterojunction bipolar transistor (HBT) HB20M technology process provided by UMS Foundry. Measurements show a relative tuning range of about 30%, an average sensitivity of about 83 MHz/V, a minimum output power of 11.4 dBm and a phase noise at 100 kHz of frequency offset from the carrier lower of −107 dBc/Hz
A Multiband 150 nm CMOS Energy Harvester Architecture
No full textWe here propose simulation results towards an integrated combined multiband IC architecture for RF energy harvesting. The proposed architecture has been designed in a 0.15 μm CMOS L-Foundry technology and optimized at three different frequencies, that is 90/900/1800 MHz. Schematic level simulations have confirmed that the proposed system is able to manage an incoming signal power typically ranging from -25 dBm to 5 dBm by rectifying the variable input signals into a DC voltage source with an average 65% efficiency. The chip area estimation. without the external antennas. is about 3 x 3 mm2
Conversion Matrix extraction by commercial CAD software for the stability design of autonomous circuits
No full textIn this paper a method to extract the conversion matrix of a nonlinear circuit by
commercial CAD simulators is proposed. As an example, the conversion matrix, computed
from a harmonic balance simulation, is used to control the stability of oscillators under large signal conditions. This allows the suppression of possible spurious frequencies or the intentional generation of spurious signals (e.g. at sub-harmonic frequency)
VCII-Based Sensor Interface for Silicon Photomultiplier
No full textWe here propose a voltage conveyor-based sensor interface for silicon photomultipliers (SiPMs). The solution addresses a mixed-mode (voltage/current) design taking advantage from the current-mode approach to increase the response time and the drive capability. This solution, based on a voltage conveyor (VCII) shows very high transimpedance gain that is independent from the bandwidth and is able to work also with a very high input parasitic capacitive impedance
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