Application of oscillation-based self-testing systems for higher order active RC low-pass filters

Abstract

In this paper, different number of stages of the active RC low-pass filters were investigated for detection range of parametric faults using on-chip built-in self-test system. As filter testing circuitry, the oscillation based self-test system was designed and used to estimate and compare the minimum range of parametric faults in low-pass filters, which are identified as uncertainty of measurement. As feedback circuit in self-test system, the high-gain inverter was used. As circuits-under-test, the Sallen-Key structure, 2nd, 4th and 6th order active RC low-pass filters with 10 MHz cut-off frequency were used. Simulations of proposed self-test system were carried out in 0.18 µm CMOS technology. The undetectable variation limits of the passive components’ nominal values in investigated low-pass filters did not exceed -0.63% ÷ +0.74% in case of 2nd order filter, ±0.54% in case of 4th order filter and ±0.62% in case of 6th order filter.