A technique for the calibration of DAC (digital to analog converter) mismatch errors in multibit ΣΔ modulators (SDM) is presented. It consists of two parts: the first is a measurement technique to obtain the relative mismatch of each feedback DAC element. The second is a correction method applied to the modulator output to correct for the effect of DAC non linearity. The proposed technique works completely in the background. The paper presents a detailed analysis of the possible error sources affecting the accuracy of the calibration, as well as a comparison with other state of the art techniques. The technique is applied to a 3rd order SDM showing almost ideal characteristics after calibration.
Morphological wavelet transform using multiple directional sampling windows is successfully implemented on a cellular hardware platform (CAM2). Several non-directional and directional sampling windows can be applied for same image. Sampling windows to be applied are selectable for each image domain. Evaluation results show that CAM2 has the potential for performing multidirectional morphological wavelet transforms at high speed.
