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Method and apparatus for testing analogue circuits

  • US 5,202,639 A
  • Filed: 02/19/1992
  • Issued: 04/13/1993
  • Est. Priority Date: 01/09/1989
  • Status: Expired due to Term
First Claim
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1. A method of testing an analogue circuit, the circuit comprising a network of electrical modules interconnected by nodes, each module comprising an electrical component or set of electrical components, the method comprising a measurement routine including the steps of(1) interfacing the circuit to automatic test apparatus, said test apparatus comprising means for interfacing with said circuit, means for applying stimuli to said circuit and means for taking test measurements from said circuit,(ii) selecting a set of stimuli, including supply potentials, for application to the circuit,(iii) applying said set of stimuli to first nodes of said circuit via said interfacing means,(iv) taking a set of test measurements from second nodes of the circuit via said interfacing means,(v) conducting at least one analysis cycle, employing the automatic test apparatus for each analysis cycle, each analysis cycle comprising the steps of(a) analyzing the circuit as a network of nodes connected by modules which impose constraints on signals passing between the nodes,(b) using the set of stimuli, the test measurements, and the constraints, taking into account tolerances in all of said stimuli, measurements, and constraints, to derive at least two differently derived ranges of values of a signal variable propagated within the network at at least one of a complete set of nodes,(c) detecting a fault if said differently derived ranges of the variable do not overlap so as to indicate an inconsistency, and(d) if a fault is detected, repeating the analysis cycle which has led to a fault being detected with the constraints on a selected module removed, other than the constraint that all the currents into the module sum to zero, and treating said selected module as potentially faulty if such removal of constraints leads to a removal of the inconsistency.

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