Signature analysis for analog and mixed-signal circuit test response compaction

While the design of signature analyzers for digital circuits has been well researched in the past, signature analyzers for analog signals are relatively unknown. The primary difficulty in analyzing signatures for analog signals is that the latter are imprecise in nature. Therefore, deterministic signature analysis schemes, such as those based on finite-field arithmetic using linear feedback shift registers, are unsuitable for analog circuits. In this paper, a novel signature analysis scheme for analog and mixed signal circuits is proposed. The signatures possess the interesting property that if the input analog signal is imprecise within certain bounds (an inherent property of analog signals), then the generated signature is also imprecise within certain bounds. A failure is indicated by the generated signature being different from the expected signature by a margin greater than a predetermined threshold; the larger the effects of the failure, the larger the difference between the generated signature and the expected signature. The probabilities of aliasing and false rejection are also derived. Results for an example filter circuit are presented.