Indian Journal of Science and Technology

Abstract

Objectives: The objective of this paper is to estimate the dynamic parameters of Analog to Digital Converter (ADC) with multi frequency sine signal as stimuli. Methods/Statistical Analysis: Traditionally the characteristics of a signal are estimated with its spectrum using Fast Fourier Transform (FFT) algorithm. Interpolated FFT technique gives more accurate results compared to the FFT technique. The signal is weighted with rectangular and Hanning window before the Discrete Fourier Transform (DFT) is calculated, frequency and magnitude of various components of input stimulus are estimated with this technique. Weighted signal is applied to ADC under test and the frequency spectrum of digital output is obtained. Findings: This technique is used to determine the frequency dependent parameters of ADC. The analytical formula for amplitude, frequency and phase estimation is simple to implement. The expression for the accurate estimation of the fractional part between the two largest spectrums of the recorded cycles by IP DFT method is presented. Sampled input signal is weighted with rectangular and tapered window and averaged. A reduction in noise level can be observed in the spectrum. The obtained values of frequency, amplitude and phase which are more accurate as presented in literature. Comparative values of ideal and real ADC dynamic parameters are presented here. The research work carried can contribute significantly to ADC design and testing with multi frequency input signals. The novelty of this approach is that the accurate results for dynamic parameters of ADC can be characterized for a particular bandwidth in a single run. Application/Improvements: An ADC is a vital component in high-speed data communications video and radar systems. The overall accuracy of the system is dependent on the accuracy of the ADC. For such systems, dynamic testing of the device using standard signal is not useful. Therefore dynamic testing of ADC under application conditions is needed. The techniques discussed in the paper are very much useful in testing high-speed ADCs by the manufacturer as well as a circuit designer.

Keywords: Analog to Digital Converter, Dynamic Parameters, Multi Frequency Signal, Multipoint Interpolation