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

随着技术规模的扩大，晶体管的固有漏损也在增加，静态电流（IDDQ）测试的有效性显著降低。基于暂态电流（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测试在数字和模拟电路故障检测方面的潜力已经确立，但目前还没有已知的利用IDD分析进行故障诊断的有效方法。提出了一种基于小波变换的IDD波形分析方法，用于数字CMOS电路的故障检测与诊断。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检测和定位故障。在8位ALU上的初步实验结果表明，考虑到过程变化和测量噪声等实际问题，基于小波变换的IDD分析具有有效检测和定位故障的潜力。暂态电流（IDD）分析对于模拟电路的缺陷检测也是有效的。我们观察到小波变换为模拟电路的故障检测提供了一种有效的分析IDD的方法。小波在时域和频域同时解析事件的特性以及比傅里叶分析更好的子带性，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来自不同电路的电流波形。我们观察到，对于相同数量的谱分量，基于小波的模拟电路故障检测灵敏度远高于傅立叶或时域分析，无论是灾难性故障还是参数故障。在基准电路上的初步实验结果表明，基于小波的方法对参数故障的灵敏度平均是DFT的25倍，可以认为是在测量硬件噪声和过程变化的情况下模拟故障检测的一种有前途的替代方法。在本文提出的研究中，我们将开发一种基于小波的混合信号电路暂态电流分析的集成故障检测和诊断方法。我们将在国内外会议上展示我们的研究成果。国际会议包括（2003年12月在澳门举行的CAD和CG国际会议；2005年在欧洲举行的IEEE设计和测试国际会议）。

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).