A 2-FFT method for on-chip spectral testing without requiring coherency

Most of the existing methods that test spectral characteristics require stringent coherent sampling. Maintaining coherent sampling is the major bottleneck in spectral testing. We propose a new method for spectral testing that completely relaxes the condition of coherent sampling. This method uses the frequency domain data to identify the non-coherent fundamental. The method is faster than other state of-the art algorithms that do not require coherency. Because of the relaxation in coherency requirement, this method is suitable for on-chip testing. Simulation results are presented to show the effectiveness of this method in the absence of coherency. A maximum error of 1dB and 1.5dB were obtained while estimating THD and SFDR respectively. The proposed 2-FFT method is successfully verified using measurement data.