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Oscillation-based test algorithm has been proposed and verified experimentally as an alternative to the specification--based test of analog circuits. Active filters are transformed to oscillators using nonlinear feedback, realized with a Schmitt trigger. Faults are detected based on the deviation of the oscillation frequency outside the tolerance band due to the variation of different circuit components under test. This proposed technique ensures high test precision due to the processing of the oscillation frequency with the help of a purely digital circuit. Undetectable ranges of parametric faults of circuit components have been identified by simulation with Cadence virtuoso using the 0.18 µm CMOS technology. Then, practical circuits of second order Butterworth Low Pass Filter and Sallen-Key Band Pass Filter have been tested experimentally. Experimental results ensure high fault coverage of the proposed test strategy. [ABSTRACT FROM AUTHOR]