DESIGN FOR TESTABILITY OF EMBEDDED INTEGRATED OPERATIONAL-AMPLIFIERS

The operational amplifier (op amp) is one of the most encountered anal og building blocks, In this paper, the problem of testing an integrate d op amp is treated, A new low-cost vectorless test solution, known as oscillation test, is investigated to test the op amp, During the test mode, the op amps are converted to a circuit that oscillates and the oscillation frequency is evaluated to monitor faults, The tolerance ba nd of the oscillation frequency is determined using a Monte Carlo anal ysis taking into account the nominal tolerance of all important techno logy and design parameters, Faults in the op amps under test which cau se the oscillation frequency to exit the tolerance band can therefore be detected, Some Design for Testability (DfT) rules to rearrange op a mps to form oscillators are presented and the related practical proble ms and limitations are discussed. The oscillation frequency can be eas ily and precisely evaluated using pure digital circuitry, The simulati on and practical implementation results confirm that the presented tec hniques ensure a high fault coverage with a low area overhead.