Energy-Efficient Amplifiers Based on Quasi-Floating Gate Techniques

Energy efficiency is a key requirement in the design of amplifiers for modern wireless applications. The use of quasi-floating gate (QFG) transistors is a very convenient approach to achieve such energy efficiency. We illustrate different QFG circuit design techniques aimed to implement low-voltage, energy-efficient class AB amplifiers. A new super class AB QFG amplifier is presented as a design example, including some of the techniques described. The amplifier has been fabricated in a 130 nm CMOS test chip prototype. Measurement results confirm that low-voltage, ultra-low-power amplifiers can be designed, preserving, at the same time, excellent small-signal and large-signal performance.

Prototype of Rainfall Intensity Measurement Using CCD TSL1401CL Linear Sensor Array

A prototype measurement of rainfall intensity was developed using a CCD TSL1401CL linear sensor array. The prototype consists of a He-Ne laser that functions as a light source, which later is focused by the beam expander and conditioned by a convex lens. Each pixel will receive the same voltage depending on the light intensity so that it produces a decimal value of ADC. This ADC decimal value determines rainfall intensity based on the diameter and velocity of the raindrops. The diameter variations used ranges from 1 mm to 10 mm, while for variations in the height of rainfall are 50 cm, 100 cm, and 150 cm. The test results proved that the greater the decimal value of the ADC is, the smaller the diameter of the raindrops detected will be, and vice versa. The values of the diameter and velocity of were used to obtain the value of rainfall intensity. The percentage value of error measuring rainfall intensity is 3.11% when compared to the rain gauge module is still considered rather accurate. However, direct testing is still needed when rain falls with various types and intensities.

High gain broadside mode operation of a cylindrical dielectric resonator antenna using simple slot excitation

In this work, the authors report the operation of a cylindrical dielectric resonator antenna (CDRA) in the high gain HEM13 δ mode, for the first time. This mode, excited with a standard microstrip slot, radiates in the broadside direction with gain in the range of 8−10 dBi. It is shown that through feed optimization, the HEM13 δ mode can be excited dominantly by suppressing the fundamental HEM11 δ mode of the CDRA. Detailed simulation studies show that the HEM13 δ mode is supported by cylindrical dielectric resonators with an aspect ratio (radius to height ratio or a/d) >1, and it resonates at a frequency approximately 2.2 times that of the fundamental HEM11 δ mode. The above features of the HEM13 δ mode CDRA can be used as approximate design rules. For a CDRA with dielectric constant ɛr = 24, diameter 2a = 19.43 mm, and height d = 7.3 mm (a/d = 1.3), the HEM13 δ mode is excited at 6.125 GHz with a peak gain of 10.14 dBi in simulation. Corresponding values from prototype measurement are 5.981 GHz and 9.62 dBi, respectively for the resonant frequency and the gain, verifying the simulation.

A rectangular slot antenna with perfectly conducting superstrate and reflector sheets for superior radiation in the 6–9 GHz band

This paper presents the design and analysis of a rectangular slot antenna for producing a directional radiation pattern over a wide bandwidth of 6–9 GHz. A basic wideband slot antenna is designed for the desired frequency band by microstrip offset feed technique. This antenna is then loaded with a superstrate and a reflector, both made of conducting sheets. Analogous to a three-element Yagi antenna, the superstrate enhances the boresight gain, while the reflector improves the front-to-back ratio (FBR) of the basic slot antenna. The antenna is optimized for superior wideband performance with boresight gain ≥5 dBi, peak cross-pol level ≤−10 dB and FBR ≥10 dB, over the −10 dB impedance band of 6–9 GHz, which in this paper is termed as the radiation bandwidth. Prototype measurement demonstrates a radiation bandwidth of 6.05–8.22 GHz (or 30.41%), which is in decent agreement with the simulation.

Performance Analysis of Cost-Effective Miniature Microphone Sound Intensity 2D Probe

This article presents the functional properties of modified versions of the 2D pressure–pressure intensity probe allowing us to determine the vector of sound intensity on a plane using a mechatronic system with one or two miniature electret microphones. The introduction contains basic information about the application areas of the sound intensity and its measurement problems. Next, the principle of operation of the probes and the construction of the prototype measurement system are described. It was subjected to comparative analysis for the stability of obtained results and accuracy of directional characteristics in free field conditions. For this purpose, experiments were conducted to analyze the flow of acoustic power in an anechoic chamber using both (one- and two-microphone) probes. The results were used for a comparative metrological analysis of the described methods and to indicate the advantages and disadvantages of both constructions. The next part of the article presents an experiment concerning the measurement of the sound intensity impulse response of a room, which is an example of practical use of the probe to analyze reflections in the room, which can be used in sound engineering and architectural acoustics.

Implementation of a New Geometrical Qualification (DQ) Method for an Open Access Fused Filament Fabrication 3D Printer

This work presents geometric qualification on rapid prototyping process in the case of open access 3D printers where a working model is proposed and a prototype measurement is presented. The problem, which is to develop a methodological approach for the realization of five test pieces of equal dimensions based on complete process knowledge of the downstream material deposit movement according to XML standards, is addressed after a state of the art review. The result allows confirming the quality of the machine recommended by the manufacturer. Basically, the adopted methodology was used to fill the vacuum in the 3D FDM (open source) 3D geometric qualification (DQ) as well as to pave the way for the 3D printing processes standardization [1].