Oscillation-based test in oversampled ΣΔ modulators

Abstract

This paper discusses a way of applying the oscillation-based test (OBT)/oscillation-based built-in-self test concept to oversampled ΣΔ modulators, exploiting previous experience coined through the implementation of OBT in SC integrated filters. Analytical and simulation results demonstrate that it is always feasible to find out an OBT configuration for a typical discrete-time second-order modulator structure without adding a substantial extra circuitry, but only resorting to local feedback loops. A feedback strategy can be chosen providing enough freedom to force oscillations, which can be worthwhile for testing purposes. The selected oscillation parameters allow us to establish criteria for a high fault coverage. © 2002 Elsevier Science Ltd. All rights reserved.