An ENOB Evaluation Method for an Acquisition Channel

Abstract

Three-parameter and four-parameter sine-wave fitting algorithms are powerful tools for estimating the parameters of the excited single-tone sine-wave for ADC. In the dynamic performance testing processes of instruments, the angle frequency, amplitude, phase and dc component of the input sine-wave are all unknown, so the fitting procedure is nonlinear. This paper proposes and analyzes a test method based on iteration Interpolated Discrete Fourier Transform (IpDFT) and sine-wave fitting method for evaluating the effective number of bit (ENOB) of the acquisition channel. Mathematical expressions of the Least-square fitting residual error and the proposed ENOB evaluation based on iteration IpDFT method are derived. These expressions are then particularized for acquisition circuit output noise composed of single-tone and additive white noise. Simulation results show that the DFT-based golden section searching algorithm (DGSSA) is an effective algorithm under coherent and non-coherent sampling conditions. The accuracy of the derived expressions and estimated parameters are verified through both the computer simulations and experimental results.