Investigation of feedback circuit for oscillation-based self-testing systems

In this paper, different types of feedback circuits for on-chip built-in self-test were investigated. As testing system, an oscillation type built-in self-test was designed and it was used to estimate parametric fault of circuit under test (CUT). As circuit under test, a second order Sallen-Key structure low-pass filter was designed and three feedback circuits were investigated, inverter, Schmitt trigger and comparator were used. Simulations of built-in self-test system were carried out in 0.18 µn CMOS technology. Transient and Monte Carlo simulations were used to investigate proposed OBIST system and feedback circuits. The detection range of parametric faults of passive components' nominal value, depending on the used feedback circuit, did not exceed -0.63% -:- 0.74% in case of high-gain inverter, -11.15% -:- 4.63% in case of Schmitt trigger and -56.19% -:- 71.57% in case of comparator.