ADC testing using interpolated fast Fourier transform (IFFT) technique

An ideal transfer characteristic of an analogue-to-digital converter (ADC) is simulated and an arbitrary nonlinearity error is introduced. A full-scale sine wave is also simulated and applied to ADC input. The interpolated fast Fourier transform (IFFT) technique is used to determine accurately fundamental and other harmonics in the output spectrum of the ADC. The signal-to-noise ratio and the effective number of bits (ENOB) are computed on the basis of FFT and IFFT for different resolutions of ADC and test conditions. The effects of rectangular and Hanning time window functions on the determination of frequency components are reported. The proposed method of dynamic testing of the ADC is useful for users as well as manufacturers.