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Publicações

Publicações por José Machado da Silva

2009

ESTIMATION OF RF PA NONLINEARITIES AFTER CROSS-CORRELATING POWER SUPPLY CURRENT AND OUTPUT VOLTAGE

Autores
Veiga, R; Mota, P; da Silva, JM;

Publicação
2009 IEEE 15TH INTERNATIONAL MIXED-SIGNALS, SENSORS, AND SYSTEMS TEST WORKSHOPS

Abstract
The present paper describes developments carried-out on estimating 1 dB compression and third-order intercept points after the cross-correlation between power supply dynamic current and output voltage of radio-frequency power amplifier. The underlining theory and a circuit that allows implementing this measurement on-chip are presented. Simulation results, including the analysis of optimum stimuli amplitudes and the Monte Carlo analysis to circuits' process variations are presented. These show that good accuracy can be obtained with relatively simple measurement conditions.

2010

Evaluation of RF Pa nonlinearities based on cross-correlation between current and output voltage

Autores
Mota, P; Da Silva, JM; Veiga, R;

Publicação
5th Conference on Design and Technology of Integrated Systems in Nanoscale Era, DTIS 2010

Abstract
The estimation of 1 dB compression and third-order intercept points can be obtained after the cross-correlation between dynamic current and output voltage of radio frequency power amplifiers. Estimation is performed using power measures and not power inferred from voltage measures. The underlining theory and a correlator that allows implementing this measurement on-chip are presented. The trade-off between measuring voltage or the actual power is also discussed. It is also shown that different information concerning the output load is obtained when observing the PA's output voltage and power. Simulation results, obtained with the model of a prototype demonstration chip show that good accuracy can be obtained with relatively simple measurement conditions. These results include the analysis of optimum stimuli amplitudes and the effect of noise in estimation accuracy. © 2010 IEEE.

2008

An Adaptive Scheme for Estimating and Correcting RF Amplifiers' Non-linearities

Autores
Mota, PF; da Silva, JM; Long, J;

Publicação
2008 IEEE ASIA PACIFIC CONFERENCE ON CIRCUITS AND SYSTEMS (APCCAS 2008), VOLS 1-4

Abstract
An adaptive amplifier scheme is presented which allows for estimating and correcting the behaviour of a non-linear amplifier, in order to improve its performance for RF communication. This is attained configuring its operating mode in one of estimation of the amplifier's non-linearity, automatic gain control, and correction of eye diagrams' opening. The theory behind these three operating modes is explained first using simulation results obtained with a behavioural model. Experimental results, obtained with a proof-of-concept prototype, which validate the functional correctness in these three modes are also presented. Issues concerning implementation requirements and limitations are discussed.

2000

DYNAD: a Framework IVSMT project addressed to the development of dynamic test techniques for analog-to-digital converters

Autores
Morandi, C; Chiorboli, G; Dallet, D; Haddadi, D; Mazzoleni, S; da Silva, JM; Pernull, H; Roy, PY;

Publicação
COMPUTER STANDARDS & INTERFACES

Abstract
DYNAD, a Standards, Measurements and Testing project supported by the European Commission within the Framework IV activities, is a research project aiming at the investigation of test procedures for evaluating the dynamic performances of A/D converters and S/H circuits. The paper concisely reports about the activities carried out in the first months of the project, activities which aim at improving the existing norms for what concerns the "classical" dynamic test methods for A/D converters, based on the use of sinusoidal stimuli. Web links are provided so that any interested party may contribute his/her opinion on the developed draft. Then, the research activities planned for the following years are briefly illustrated.

2008

A pull-in based test mechanism for device diagnostic and process characterization

Autores
Rocha, LA; Mol, L; Cretu, E; Wolffenbuttel, RF; MacHado Da Silva, J;

Publicação
VLSI Design

Abstract
A test technique for capacitive MEMS accelerometers and electrostatic microactuators, based on the measurement of pull-in voltages and resonance frequency, is described. Using this combination of measurements, one can estimate process-induced variations in the device layout dimensions as well as deviations from nominal value in material properties, which can be used either for testing or device diagnostics purposes. Measurements performed on fabricated devices confirm that the 250nm overetch observed on SEM images can be correctly estimated using the proposed technique.

2010

Estimation of RF PA Nonlinearities after Cross-correlating Current and Output Voltage

Autores
Mota, PF; Machado da Silva, JAM; Veiga, RA;

Publicação
JOURNAL OF ELECTRONIC TESTING-THEORY AND APPLICATIONS

Abstract
The estimation of 1 dB compression and third-order intercept points can be obtained after the cross-correlation between dynamic current and output voltage of radio frequency power amplifiers. This estimation is performed using actual power measurements and not power inferred from voltage values. The underlining theory and a correlator that allows implementing this measurement on-chip are presented. The trade-off between measuring voltage and the actual power is also discussed and it is shown that different information concerning the output load is obtained when observing the PA's output voltage and power. Simulation results, obtained with the model of a prototype demonstration chip, show that good accuracy can be obtained with relatively simple measurement conditions. These results include the analysis of optimum stimuli amplitudes and the effect of noise in estimation accuracy.

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