Error modelling has played a major role in generating post-corrections of analogue to digital converters (ADC). Benefits by using parametric models for post-correction are that they requires less memory and that they are easier to identify for arbitrary signals. However, the parameters are estimated in two steps; firstly, the integral nonlinearity (INL) is estimated and secondly, the model parameters. In this paper we propose a method to improve the performance in the second step, by utilizing information about the statistical properties of the first step.

An input-dependent integral nonlinearity (INL) model is developed for pipeline ADC post-correction. The INL model consists of a static and dynamic part. The INL model is subtracted from the ADC digital output for compensation. Static compensation is performed by adjacent sets of gains and offsets. Each set compensates a certain output code range. The frequency content of the INL dynamic component is used to design a set of filter blocks that performs ADC compensation in the time domain. The compensation scheme is applied to measured data of two 12-bit ADCs of the same type (Analog Devices AD9430). Significant performance improvements in terms of spurious free dynamic range (SFDR) are obtained.

For automatic correction of measurement transducer error additive iterative method (AIM) could be used. But quantization error represents limitation for correction process in application for analog-to-digital converter. Combination of AIM with nonsubtractive dithering (ND) is proposed for this kind of application and the principle of combination of both techniques is described in the paper. AIM is based on precise inverse element (IE) which in our case consists of pulse width modulation output and low-pass filter. Technique similar to deterministic dithering is employed to achieve precise processing of signal from IE. Analysis of influence of dither with uniform distribution upon the results of correction is performed with the aim to find optimal parameters of ND. The optimal dispersion of dither is found leading to meaningful error correction. Finally dependency of root mean squared error on measured value is drawn to show how AIM improves accuracy.

The methodology and experimental results of the researches for thermal instability of reference clock generator in microcontroller based frequency-to-code converters with virtual channel are described in the Paper. The temperature uncertainty of the frequency and time references, distribution laws and correlation factor of their errors were determined in the experiments. The maximum relative temperature error of the frequency reference is ± 11.5 · 10^-6, and the maximum temperature error of the time reference is ± 0.38 · 10^-6. The total relative error of the “measurement standard” in the microcontroller based frequency-tocode converters is equal to ± 10.9 · 10^-6. The obtained results are used at research of the limiting metrological characteristics for microcontroller based measuring instruments of frequency/time parameters with virtual measuring channel.

The paper deals with the research and analysis of up-to-date system approach to SI AD conversion focused to pressure smart sensors for system integration. Built-in self-testing improves quality and reliability of analogue to digital conversion. This trend is encouraged by industrial implementation of pressure smart sensors including AD converter into sensor/actuator fieldbus driven systems.