Effect of Noise on Analog Circuit Testing

  • Authors:
  • Madhu K. Iyer;M. L. Bushnell

  • Affiliations:
  • Dept. of ECE, University of California, Santa Barbara, CA 93106, USA. madiyer@yellowstone.ece.ucsb.edu;CAIP Research Center and ECE Dept., Rutgers University, Piscataway, NJ 08854, USA. bushnell@caip.rutgers.edu

  • Venue:
  • Journal of Electronic Testing: Theory and Applications
  • Year:
  • 1999

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Abstract

The effect of test environment noise (tester noise) on testwaveforms is considered. We show that tests generated ignoring thetester noise characteristics are prone to failure when actuallyapplied to the circuit-under-test (CUT). The failure may result inthe good circuit being declared faulty or the faulty circuit beingdeclared good. This failure is independent of the fault model andnature of the test, i.e., AC or DC, time domain or frequency domain.We characterize the total noise at the primary outputs (PO‘s) of thecircuit using second order statistics. We use the noise powerspectrum and root mean square (RMS) values to make decisions aboutthe test waveforms and recommend more noise-robust tests. Fornon-linear circuits we use the Central Limit Theorem of statistics toapproximate narrow band noise at a primary input (PI) by a sum ofsinusoidal distributions, and we use Monte-Carlo simulations todetermine the noise at the PO‘s in the time domain. Results ofexperiments on an instrumentation amplifier, a biquadratic filter,and a Gilbert multiplier are presented, which prove that valid testsin a noise-free environment are invalid when tester noise isconsidered.