Franco Maloberti
HIGH-SPEED HIGH-RESOLUTION DATA CONVERTERS FOR BASE STATIONS: TECHNOLOGIES, ARCHITECTURES AND CIRCUIT DESIGN

This paper presents a possible evolution of base station architectures in the frame of the future global communication scenario. Moving from such a view the paper considers the technology trend and its influence on highspeed data converter design. Then, architectures of highspeed, high-resolution converters are resumed. Finally, design techniques and strategies for achieving the requirements of base-station systems are discussed.

A.A. Platonov, L.M. Malkiewicz, K. Jedrzejewski
ADAPTIVE CADC OPTIMISATION, MODELLING AND TESTING

Analytical approach to optimization, analysis, modeling and testing of the adaptive cyclic (sub-ranging) analog-to-digital converters (CADC) is considered. The particularity of the approach is digital computing the estimates (codes) of the input signal samples using optimal signal - processing algorithm. Upper boundaries for resolution, speed of conversion, and information characteristics are determined. Methodic of advanced CADC model-based simulation investigations is presented. The efficiency of simulation experiments as reliable, convenient and low-cost tool significantly simplifying and accelerating the search for optimal variants, design and analysis of CADC is shown.

Henrik Lundin, Patrick Svedman, Xi Zhang, Mikael Skoglund, Peter Händel, Per Zetterberg
ADC IMPERFECTIONS IN MULTIPLE ANTENNA WIRELESS SYSTEMS—AN EXPERIMENTAL STUDY

This paper investigates some of the effects that ADC imperfections may have on wireless communication systems. First, an experimental communication system for wireless multiple-input multiple-output (MIMO) is described. In this test bed, an ADC behavioural model has been implemented. The resulting performance of the communication system, in terms of bit error rate, is assessed when the parameters of the ADC model are altered. The results show that, for this system, the ADC resolution is the key parameter while the non-linearity errors are of minor importance.

J. Halámek, I. Višcor, M. Kasal, M. Villa, P. Cofrancesco
STATIC AND DYNAMIC A/D CONVERTER NONLINEARITY

The ADC’s static and dynamic nonlinearity with relation to harmonic distortion and parameters describing the nonlinearity are discussed. The commonly used description by INL and hysteresis is acceptable only if the dynamic nonlinearity is significantly lower than the static nonlinearity. The significance of dynamic nonlinearity is presented on the measurement and the analysis based on complex spectrum is demonstrated. We call the attention to more detailed tests of ADC according to the dynamic nonlinearity and definition of an optimal working point with maximal SFDR.

Vladimir Haasz, David Slepicka
FREQUENCY SPECTRUM CORRECTION TEST – PRACTICAL EXPERIENCE

The main problem of the high resolution ADC testing within the frequency range hundreds of kHz to several MHz is the spectral purity of a testing signal. Commercially produced low-distortion generators have the spectral purity sufficient for testing of 16 bits ADCs only up to frequencies of tens of kHz; at higher frequencies the spectral purity of generators is generally worse. Some improvement can bring signal filtering. However, most of the LC filters use coils with ferromagnetic cores for the frequency range up to several hundreds of kHz, which can cause a rise of odd harmonic components. Nevertheless, these components can be measured and subtracted from the spectrum calculated from ADC output data. In the ideal case, only the frequency spectrum corresponding to the ADC non-linearity remains. An ADC measurement system was designed and built for the verification of this method in the frequency range 200 kHz to 1 MHz. The practical experience of its application is described in this paper.