The paper deals with the state of art on the tests for both ΣΔ modulators and ΣΔ Analog to Digital Converters (ADCs). Particular aspects are highlighted concerning the tests for the innovative architectures based on the Band Pass ΣΔ ADC. The analysis of the tests is carried out in conjunction with the discussion about the applicability of the procedures included into the IEEE Standard 1241. Therefore, three fundamental groups of tests are defined: (i) tests according to the IEEE Standard 1241, (ii) tests included into the IEEE Standard 1241 but executed in a different way from the Standard,...
The sine wave test is maybe the most important method for characterizing ADC’s. By this, the acquisition device is excited with a sinusoidal signal, and a long series of output values is measured. With the help of these observations, the parameters of the DUT can be determined. The general method to do this is the Least Squares (LS). In this paper, we present a similar method using the Maximum Likelihood Estimation (MLE). It is more robust than the LS method, which has nice properties only under special conditions. This maximum likelihood problem is solvable only numerically. For this, a...
This paper describes a technique mitigating the impact of timing mismatches in timeinterleaved analog-to-digital converters (ADCs). The systems signal-to-noise and distortion ratio (SINAD) and spurious-free dynamic range (SFDR) are increased by controlling the selection order of the channels ADCs in combination with oversampling and consecutive filtering. The proposed method requires only knowledge of the relative level of timing mismatch between the channel ADCs though not the precise magnitude of the mismatch. The impact of timing mismatch on the SINAD and advanced selection ordering...
Based on a model of a test signal generator, an accuracy estimator was designed and implemented. The proposed estimator uses computer simulations to obtain expected bias of dynamic parameters of an analog-to-digital converter (ADC). The usage of the method for estimation of ADC dynamic parameters measurement accuracy for the best sine-wave fit and the frequency domain analysis using the DFT will be presented in this paper
In the last several years, many high-resolution and high-speed ADCs have appeared on the market. Since the signal purity of commercial generators particularly at MHz frequencies has not essentially increased in the same period, the problem of how to test ADCs has rose. This fact initiated the research of alternative methods based on either the application of special signals or posteriori correction of the measured sine-wave signal. The latter method concerning a simple correction in the frequency domain was analyzed, extended and practically applied. The application and the results of this...
The main goal of this paper is to introduce several definitions of noise floor and to show their application in ADC testing with regard to straightforward reading of some basic ADC parameters. The definitions and algorithms can be used for ADC standardization.
This paper deals with the virtual testing environment for analog-to-digital converters (ADCs) employing a novel and powerful extension of the Servo-Loop method. We build an improved version of the Servo-Loop targeted to full transistor-level circuit simulation of static integral and differential ADC non-linearity. In comparison with the conventional implementation, the Servo- Loop version proposed was enhanced by an effective search algorithm. The algorithm was implemented as a versatile Servo-Looper tool written in Verilog-A language which is suitable for direct co-operation with most of...
This paper presents some typical errors of exponential stimulus generated by analog signal sources and their influence on errors of ADC testing by the histogram method. The analysed exponential signals are very close to linear signals such as triangular and sawtooth signals that can be very simply generated by active integrating circuit or passive integrating circuit with long time constant and/or the final voltage far beyond the ADC input range. The experimental measurements of some analogue generators on the market as well as passive and active generating circuit specially designed for the...
This paper demonstrates two methods of noise signal generation for ADC testing. Digital pseudo-random number generator based on LFSR and combinations of LFRS are used. The objective of this exploration is to develop device for generation noise signal with uniformly distributed amplitudes. The signal should be used to measure parameters of AD converters using histogram test method.
This paper compares two basic procedures used in estimations of the significant components in the residual spectrum in the ADC dynamic testing. The properties of the weighted DFT interpolations for the frequency, amplitude, and phase estimations in order to reduce the leakage effect of the fundamental component in the investigation of the residual spectrum is described. The nonparametric interpolation algorithms retain all benefits of DFT approaches and improve the estimation accuracy as a function of a number of the signal cycles in the estimation interval. The comparison of the three-point...