Oscillation-test methodology for low-cost testing of active analog filters

TLDR

The oscillation‑test strategy offers a low‑cost, robust, vectorless method for mixed‑signal ICs, enabling precise digital analysis of oscillation frequency and easy interfacing with digital test techniques. The paper presents a design‑for‑testability approach for active analog filters using oscillation‑test methodology. Active filters are converted into oscillators by simple techniques, and the oscillation frequency tolerance band is set via Monte Carlo analysis of component tolerances. Simulations and practical realizations using CMOS 1.2 µm technology show that the proposed test technique achieves high fault coverage with negligible area overhead, and the DFT methods are well suited for automatic testable filter synthesis and integration into design tools.

Abstract

The oscillation-test strategy is a low cost and robust test method for mixed-signal integrated circuits. Being a vectorless test method, it allows one to eliminate the analog test vector generator. Furthermore, as the oscillation frequency is considered to be digital, it can be precisely analyzed using pure digital circuitry and can be easily interfaced to test techniques dedicated to the digital part of the circuit under test (CUT). This paper describes the design for testability (DFT) of active analog filters based on oscillation-test methodology. Active filters are transformed to oscillators using very simple techniques. The tolerance band of the oscillation frequency is determined by a Monte Carlo analysis taking into account the nominal tolerance of all circuit under test components. Discrete practical realizations and extensive simulations based on CMOS 1.2 /spl mu/m technology parameters affirm that the test technique presented for active analog filters ensures high fault coverage and requires a negligible area overhead. Finally, the DFT techniques investigated are very suitable for automatic testable filter synthesis and can be easily integrated in the tools dedicated to automatic filter design.