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Publicações

Publicações por José Silva Matos

2001

ADC testing using joint time-frequency analysis

Autores
Mendonca, H; da Silva, JM; Matos, JS;

Publicação
COMPUTER STANDARDS & INTERFACES

Abstract
Analog-to-digital converter (ADC) characterization is usually performed using stationary stimuli like sine waves. However, the use of a non-stationary stimulus, besides providing testing conditions closer to those found in real applications, can lead to interesting improvements in ADC testing speed, This kind of signal needs proper processing techniques in order to extract useful information. In this paper we propose the use of joint time-frequency analysis (JTFA) for this purpose. The basic principles of the technique, and how it can be used in ADC testing are presented. in particular, a method for characterising an ADC on its entire bandwidth using a single stimulus is described.

2002

Functional in-circuit characterisation of Sigma Delta modulators

Autores
da Silva, JM; Duarte, JS; Matos, JS;

Publicação
MEASUREMENT

Abstract
A method for the in-circuit functional testing of SigmaDelta modulators is described which can be built in large integrated circuits or systems-on-chip. It allows for measuring gain and phase, as well as total harmonic distortion and signal to noise and harmonic distortion ratio parameters. This method can be built in-circuit using existing computational resources, such as digital signal processors or (re)configurable logic, which can therefore be used to implement both mission and test operations. Both simulation and experimental results were obtained which are in close agreement with those expected from the theory.

2003

Computing ADC harmonic content from a reduced number of values

Autores
Mendonca, HS; da Silva, JM; Matos, JS;

Publicação
IMTC/O3: PROCEEDINGS OF THE 20TH IEEE INSTRUMENTATION AND MEASUREMENT TECHNOLOGY CONFERENCE, VOLS 1 AND 2

Abstract
The estimation of the harmonic content of an ADC output is fundamental to evaluate its suitability to perform according the requirements specified for an application. The use of the traditional frequency analysis leads to a large hardware overhead due to the amount of on-chip processing being involved, or to a large quantity of data to be transferred in case the processing is performed in a tester. This paper presents an algorithm capable of estimating the harmonics with similar accuracy but with the advantage of being more suitable for a BIST implementation, since it requires a reduced number of on-chip operations, and that only a small set of values has to be supplied outside the chip for further processing. It relies, on the fact that harmonics generated by an ADC are mathematical related with the polynomial coefficients of its transfer function. ADC offset and gain errors can also be measured.

2005

A processor for testing mixed-signal cores in System-on-Chip

Autores
Duarte, F; da Silva, JM; Alves, JC; Pinho, GA; Matos, JS;

Publicação
DSD 2005: 8th Euromicro Conference on Digital System Design, Proceedings

Abstract
This paper describes the design of a processor specific for testing cores embedded in system-on-chip. This processor which can be implemented within a system's reconfigurable area, shall be responsible for scheduling and control test operations and perform preliminary data processing, as well as to provide the interface with an external tester Building these test operations on-chip allows for simplifying external tester interface and to reduce testing time. The testing procedure and the infrastructure required to test an AID converter is described as an example.

2007

Design of circuits and integrated systems

Autores
Teixeira, JP; Matos, JS; Tomas, J; Teixeira, IC;

Publicação
IET COMPUTERS AND DIGITAL TECHNIQUES

Abstract

2008

Estimation of analogue-to-digital converter's signal-to-noise plus distortion ratio using the code histogram method

Autores
Mendonca, HS; da Silva, JM; Matos, JS;

Publicação
IET SCIENCE MEASUREMENT & TECHNOLOGY

Abstract
A procedure is proposed to estimate an analogue-to-digital converter's signal-to-noise plus distortion ratio using the histogram method. The procedure provides results that are in close agreement with the ones obtained with the spectral analysis and sinewave fitting methods. It is shown that the errors obtained by using former implementations of the histogram method are due to not considering the input stimulus probability density function, and it is shown how these errors can be rectified.

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