Fault Detection and Diagnosis for Mixed-Signal Circuits Using Wavelet Based Transient Current Analysis

由于晶体管的本征漏电流随工艺规模的增大而增大，静态电流（IDDQ）测试的有效性大大降低。基于瞬态电流（IDD）的测试经常被引用和研究，作为数字CMOS电路中IDDQ测试的替代和/或补充。虽然IDD测试的故障检测的潜力已经建立了数字和模拟电路，有没有已知的有效的方法，故障诊断使用IDD分析。提出了一种基于小波变换的IDD波形分析的CMOS数字电路故障检测与诊断的新方法。利用小波变换对IDD波形进行时域和频域分解。IDD信号的时频分辨率有助于我们检测和定位故障。在一个8位ALU上的初步实验结果表明，基于小波的IDD分析有可能有效地检测和定位故障，考虑到实际问题，如工艺变化和测量噪声的影响。 瞬态电流（IDD）分析也可以有效的模拟电路的面向缺陷的测试。我们观察到，小波变换呈现出一种有效的方法来分析IDD在模拟电路中的故障检测。小波分析具有时、频域同时分辨同相轴的特性，以及比傅立叶分析更好的分带特性，使其成为IDD分析的有效工具。此外，小波变换可以很容易地适应不同电路的电流波形。我们已经观察到，对于相同数量的谱分量，基于小波的模拟电路故障检测的灵敏度比傅立叶或时域分析的灾难性和参数故障高得多。 基准电路上的初步实验结果表明，基于小波的方法是平均25倍以上的参数故障DFT的敏感性，可以被认为是一个有前途的替代模拟故障检测测量硬件噪声和过程的变化。本研究将发展一套以小波分析为基础的混合信号电路暂态电流分析的整合式故障侦测与诊断方法，并将在国内外研讨会上发表研究成果。国际会议包括（2003年12月在澳门举行的CAD和CG国际会议，以及2005年CAD和CG国际会议;欧洲IEEE设计与测试）。

As intrinsic leakage in transistor increases with technology scaling the effectiveness of quiescent current (IDDQ) testing reduces significantly. Transient current (IDD) based testing has been often cited and investigated as an alternative and/or supplement to IDDQ testing in Digital CMOS circuits. While the potential of IDD testing for fault detection has been established for digital and analog circuits, there is no known efficient method for fault diagnosis using IDD analysis. We propose a novel integrated method for fault detection and diagnosis in digital CMOS circuits using IDD waveform analysis using wavelet transform. We use wavelet transform to decompose the IDD waveform in both time and frequency domain. The time-frequency resolution of the IDD signal helps us detect as well as localize faults. Initial experimental results on an 8-bit ALU show that wavelet based IDD analysis has the potential to efficiently detect and localize faults considering practical issues like effect of process variation and measurement noise. Transient current (IDD) analysis can also be effective for defect oriented testing of analog circuits. We observe that wavelet transform renders an efficient way for analyzing IDD for fault detection in analog circuits. The property of wavelet for resolving events in both time and frequency domain simultaneously and the property of better sub-banding than Fourier analysis, makes it a effective tool for IDD analysis. Moreover wavelet transform can be easily adapted to current waveforms from different circuits. We have observed that for equivalent number of spectral components, sensitivity of wavelet based fault detection in analog circuits is much higher than fourier or time-domain analysis for both catastrophic and parametric faults. Initial experimental results on a benchmark circuit show that wavelet based method is on average 25 times more sensitive than DFT for parametric faults and can be considered as a promising alternative for analog fault detection amidst measurement hardware noise and process variation. In the proposed research we will develop an integrated fault detection and diagnosis methodology using wavelet based transient current analysis for mixed-signal circuits.We will present the results of our research in domestic and international conferences. International conferences include (International Conference on CAD and CG in Macau, December 2003, and International Conference on CAD and CG 2005; IEEE Design and Test in Europe).