Métodos de calibração baseados em modelo para conversores analógicos-para-informação do tipo pré-integrador de modulação aleatória.

Abstract

In this thesis, we propose calibration methods for analog-to-information converters (AIC) based on the random modulation pre-integrator architecture. In a state-of-the-art search about AIC calibration, it has been found that implementations of this kind of converter frequently suffer the impact of hardware non-idealities in the signal reconstruction step. In addition, it was verified that the solutions addressed by several works make use of blind calibration methods, which is a procedure in which the calibration coefficients are acquired together with the sparse signal to be recovered, by means of a reconstruction algorithm. However, the reconstruction performed by these algorithms does not always guarantee a satisfactory result, since the input parameters influence the reconstruction of the signal. Therefore, to avoid the influence of reconstruction algorithms in the calibration process, the methods proposed in this thesis use only the measurements performed by the AIC’ hardware and those obtained by its dynamic model, so that the calibration coefficients (gain, offset and delay errors) are known before the reconstruction step, thus removing the influence of the algorithm on the accuracy of the signal reconstruction. Experiments and simulations were performed with one, two and three tone signals, and evaluation metrics were used to evaluate the measurement performed by the converter and the signal reconstruction (performed by two different reconstruction algorithms). As an example of metrics, we used the signal-to-noise and distortion ratio (SINAD), the mean square error and the reconstruction signal-to-noise ratio. From the results, the efficiency of the methods was verified by means of an improvement of 82.2%, 28.2% and 48.7% of the SINAD value of calibrated measurements of one, two and three tone signals, respectively, taking simulated measurements as ideal values. As a result of improvements in calibrated measurements, there was also a significant improvement over signal reconstruction metrics.