2013
Authors
Oliveira, C; Almeida, N; da Silva, JM;
Publication
2013 IEEE 3RD PORTUGUESE MEETING IN BIOENGINEERING (ENBENG)
Abstract
A direct arterial pressure monitoring system for post EVAR procedure based on inductive-coupling is presented which avoids the need for more complex biomedical imaging systems. Post stent-graft implantation complications, such as endoleaks, can be detected with capacitive pressure sensors placed in the stent-graft and monitored externally after the measurement of the oscillation frequency of a LC resonant circuit created by sensors and inductive coupling. Several measurements were performed in order to characterize the system and compare the results with the expected values based on theoretical models. Different measurements were carried-out with the purpose of evaluating the system's frequency detection accuracy throughout the working bandwidth and varying distances between the reader and the sensors. Both air and a phantom with electrical characteristics similar to the human body were used between the reader and the sensors antennas in order to evaluate the influence of the transmission medium. It is shown that in both cases the system is capable of detecting the oscillation frequencies, even in the case a cluster of sensors is used.
2013
Authors
Cardoso, JP; da Silva, JM;
Publication
2013 8TH INTERNATIONAL DESIGN AND TEST SYMPOSIUM (IDT)
Abstract
Tinting is a critical issue in communication systems, especially for synchronous communications. These show a high dependence on the clock signal purity due to errors that can be introduced into the decision process. This paper addresses the design, on a 130nm CMOS process, of a Radiation Tolerant Voltage Controlled Quartz Crystal Oscillator (VCXO), including techniques to reduce the influence of radiation and noise on its performance. The VCXO is included on a PLL designed to work within High Energy Physics (IIEP) experiments.
2013
Authors
Soares, C; Moreira, RS; Torres, JM; Sobral, P;
Publication
ISRN Machine Vision
Abstract
2013
Authors
Bahubalindruni, P; Tavares, VG; Barquinha, P; Martins, R; Fortunato, E;
Publication
2013 IEEE EUROCON
Abstract
Transparent TFT technologies, with amorphous semiconductor oxides are lacking a complementary type transistor. This represents a real challenge, when the design of high-gain amplifiers are considered, without resorting to passive resistive elements. However, some solutions do exist to overcome the lack of a p-type transistor. This paper then presents a comparison analysis of two high-gain single-stage amplifier topologies using only n-type enhancement transistors. In these circuits, high gain is achieved using positive feedback for the load impedance. The comparison is carried out in terms of bandwidth, power consumption and complexity under identical bias conditions. Further, the same load impedance is used to develop a novel high-gain multiplier. All the circuits are simulated using a 0.35 mu m CMOS technology, as it is easy to test the reliability of the methods, since CMOS transistors have trustworthy models.
2013
Authors
Bahubalindruni, PG; Tavares, VG; Barquinha, P; Duarte, C; de Oliveira, PG; Martins, R; Fortunato, E;
Publication
JOURNAL OF DISPLAY TECHNOLOGY
Abstract
This paper characterizes transparent current mirrors with n-type amorphous gallium-indium-zinc-oxide (a-GIZO) thin-film transistors (TFTs). Two-TFT current mirrors with different mirroring ratios and a cascode topology are considered. A neural model is developed based on the measured data of the TFTs and is implemented in Verilog-A; then it is used to simulate the circuits with Cadence Virtuoso Spectre simulator. The simulation outcomes are validated with the fabricated circuit response. These results show that the neural network can model TFT accurately, as well as the current mirroring ability of the TFTs.
2013
Authors
Bahubalindruni, P; Tavares, VG; de Oliveira, PG; Barquinha, P; Martins, R; Fortunato, E;
Publication
2013 IEEE INTERNATIONAL CONFERENCE OF ELECTRON DEVICES AND SOLID-STATE CIRCUITS (EDSSC)
Abstract
A high-gain amplifier topology, with all single n-type enhancement transistors, is proposed in this paper. This type of circuits are essential in transparent TFT technologies, such as GIZO and ZnO that lack complementary type transistor. All circuits were simulated using BSIM3V3 model of a 0.35 mu m CMOS technology, due to the absence of a complete electrical model for the TFTs. Results reveal that the proposed circuit promise more gain, lower power consumption and higher bandwidth than the existing solutions under identical bias conditions.
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