9762 papers found
It is necessary to keep at the disposition test signals with a high spectral purity for series measuring e.g. in the area of metrology or electronics. Commercial signal generators do not satisfy higher requirements in this area. Our contribution describes chances of the improvement of their quality while using of suitable filters. There is described the construction of a special generator with a high spectral purity of a signal.
This paper addresses the uncertainty of the estimates of ADC testing obtained with the Histogram Method when a triangular stimulus is used. Expressions are presented for the computation of the standard deviation of the transition voltages and code bin widths. These can be used for the Ramp Vernier Test which is a novel test method which will be included in the new version of the IEEE 1057 standard currently in balloting.
The paper presents an improved implementation of a method pointed out for the static characterization of the new generation of high resolution Digital to Analogue Converters (DACs). Interesting aspect of this method is that the problem of the signal acquisition with high resolution is shifted to the simpler problem of the signal acquisition with high speed. In particular, the method is based on the comparison of the DAC output voltage with the analogue reference sinusoidal voltage and the detection of the Zero Crossing Sequence (ZCS) of the resulting signal by high speed ADC. The variation...
Sigma-delta modulator based digital-to-analog converters (DAC) have offered low-frequency designers a highly linear, high resolution data converter architecture that is highly amenable to integration with complex digital systems. Increasingly these data converters have been used to deliver all the power needed. In wireless applications, it is increasingly desirable to apply low-frequency sigma-delta techniques to RF signals and try to achieve similar benefits. In this paper we discuss the unique challenges that DACs in mobile phone basestations must satisfy and we present a flexible bandpass...
The main point of new approach to the theory of sigma-delta modulation is application of a discrete two-values distribution law for a quantization noise instead of a uniform distribution law accepted before. Due to the new approach, the variance (standard deviation in the square) of the quantization noise becomes dependent on input signal by parabolic function. The noise vs. frequency is found for different input signals taking into account all frequency range from zero to half of sampling frequency. Using dependence of standard deviation on input signal and frequency, different...
The advantages of a signal processing in the logarithmic domain are recently pointed out by some authors. On the other hand, suitable logarithmic input amplifiers are available in the literature. The traditional logarithmic amplifier configuration based on a voltage operational amplifier with a diode connected transistor in its feedback loop, which displays a significantly reduced bandwidth at lower signal levels, was modified replacing the operational amplifier by a transconductance feedback amplifier. This solution overcomes the said problem completely and offers constant-bandwidth...
In this paper the idea and the selected results of numerical simulation of an uncertainty designation procedure in the measurement channel equipped with ADC is presented. The basic principles of that procedure implementation are shown in literature. The assessment of correctness of the mentioned procedures is the main aim of the carried out simulations.
The possibility to use the Curve Fitting Algorithm (CFA), for the Power Quality (PQ) parameters valuation foreseen by the EN 50160 Rule, is faced in terms of frequency determination. The comparison between the loop algorithm performance in the frequency determination and the thrown one, using a Taylor Series, truncated in terms of foreseen uncertainty, is presented.
In this paper a dynamic behavior model of analog to digital converters is proposed. The model is aimed for post correction in wideband applications. The suggested post correction method is a combination of look up tables and model based correction. The model consists of three components. The first is a component represented by a Hammerstein model; that is a static nonlinearity followed by a time invariant linear filter. The second component is a nonparametric model caused by significant deviation from the characterized integral nonlinearity and the output from the Hammerstein model. The...
The main purpose of this paper is to present the external correction of analog to digital converters (ADC) integral nonlinearity and quantization noise based on the look up table method combined with the averaging filter and dithering method. The low code frequency component of integral nonlinearity ( LCF INL) is reduced by the error table of the look up table method, the high frequency part ( HCF INL) by sine wave dithering signal mainly.