Low-voltage low-power CMOS RF low noise amplifier

In this paper, a 1 V, 2 GHz CMOS low-noise amplifier (LNA) was developed intended for use in the front-end receiver. The circuit is simulated in standard $0.25\mathrm{\mu }\mathrm{m}$ CMOS MOSIS. The LNA gain is 25.675 dB, noise figure (NF) is 4 dB, reverse isolation $(S_{12})$ is $-134.3\mathrm{dB}$, input return loss $(S_{11})$ is $-14.6\mathrm{dB}$, output return loss $(S_{22})$ is $-13.34\mathrm{dB}$, and the power consumption is 5.13 mA from a single 1 V power supply. One of the features of the proposed design is using a three-component cascode limitation, one of it is a transistor, to reduce the supply voltage.     

Study on the physical properties of europium doped indium oxide thin films

Structural, morphological, optical and electrical properties of europium doped In₂O₃ thin films grown by spray pyrolysis technique are studied in this work. The atomic percentages of europium dopant in In₂O₃-based solution were y = ${\left(\frac{{[\mathit{Eu}}^{3+}]}{{[\mathit{In}}^{3+}]}\right)}_{\mathit{sol}}$=0; 0.1; 0.3 and 0.5 at%. All films crystallize into the body centered cubic structure. The preferred orientation peak along the (222) plane was changed to (400) after doping. It is further revealed a best crystallinity for y =0.3 at% followed by a noticeable increase of the grain size. Some structural and microstructural parameters are determined using Rietveld refinement of XRD patterns. The optical transmission of doped films was above 68% in the visible range. The optical band gap (E_g) is in the range of [3.43–3.51] eV. Optical constant such as refractive index (n), packing density (p), porosity, oscillator energy (E₀) an_d dispersive energy (E_d) were also studied in this report using envelope method based on transmission-reflection spectra. Electrical properties show a lowest resistivity (ρ) for a doping concentration equals to 0.3 at% reaching 0.031 Ω cm. At this doping ratio, an enhancement of free carrier concentration is also remarked. A heat treatment under nitrogen atmosphere is then applied on optimized In₂O₃:Eu (0.3 at%). A significant decrease of the resistivity is noted at 250 °C during 2 h reaching 0.004 Ω cm. These results lead to conclude that annealed In₂O₃:Eu(0.3 at%) can be a good candidate to be used in many optoelectronic devices and especially as optical window or transparent electrode in solar cells.     

Low complexity PAPR reduction techniques for clipping and quantization noise mitigation in direct-detection O-OFDM systems

We present different distortionless peak-to-average power ratio (PAPR) reduction techniques that can be easily applied, without any symmetry restriction, in direct-detection (DD) optical orthogonal frequency division multiplexing (O-OFDM) systems based on the fast Hartley transform (FHT). The performance of DD O-OFDM systems is limited by the constraints on system components such as digital-to-analog converter (DAC), analog-to-digital converter (ADC), the Mach–Zehnder modulator (MZM) and electrical amplifiers. In this paper, in order to relax the constraints on these components, we propose to symmetrically clip the transmitted signal and apply low complexity (LC) distortionless PAPR reduction schemes able to mitigate, at the same time, PAPR, quantization and clipping noise. We demonstrate that, applying LC-selective mapping (SLM) without any additional transform block, the PAPR reduction is $1.5\text{dB}$ with only one additional FHT block using LC-partial transmit sequence (PTS) with random partitions; up to $3.1\text{dB}$ reduction is obtained. Moreover, the sensitivity performance and the power efficiency are enhanced. In fact, applying LC PAPR reduction techniques with one additional transform block and a 6 bit DAC resolution, the required receiver power for 8 dB clipping level and for a ${10}^{-3}\text{BER}$ is reduced by $5.1\text{dB}$.