eRNA: Refining of reconstructed digital waveform

This paper describes about capturing waveform and eye pattern of high-speed digital interface signals by using ATE (Automated Test Equipment) digital channels. In order to effectively capture digital waveform using digital channels, the DNA (Data aNAlysis) method was developed. Multiple scans of functional tests are performed with changing compare-threshold step-wise, constructing a two-dimensional mosaic waveform image, which is converted to a single-dimensional waveform at the end. Because of multiple scans, the DNA is not immune to jitter and phase drift of the signal. Phase fluctuation creates inconsistent effect across scans. Consequently, the constructed image is collapsed; parametric evaluation of the waveform turns impossible. The RNA (Recovering aNAlysis) method was developed for resolving the weak point of DNA. A reference signal is introduced to correct dislocation of waveform slices. However, the processing method was on the way to formalize and not well accomplished at that time. The Sampler Method was developed for waveform samplers equipped in mixed signal ATE. Samplers perform under-sampling to reconstruct test signal waveforms. Phase fluctuation in the signal is a kind of PM (phase modulation), smearing the captured waveform. A set of signal processing was developed to refine blurred image into a clean waveform. In this paper, the eRNA (Enhanced RNA) method is introduced. The Sampler Method is implemented into the original RNA. It demodulates the phase drift to refine each scan result. Dislocation across scan-slices is corrected by tracing the reference alignment. The eRNA restores the clean waveform from a collapsed image. The eRNA enhances the original RNA generalized. The application range of DNA/RNA was expanded. Examining the extracted phase trends enables jitter analyses. Additionally, after removing LF (Low Frequency) phase drift such as SSC (Spread Spectrum Clocking), the PM modulation processing emulates the waveform that the HF (High Frequency) jitter affects.