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

Oscillation-based test in a CCII-based bandpass filter

“…short circuits between Vdd and Vss) that 3.33 µs do not affect the oscillation frequency or the amplitude but they have an easily noticeable effect in the IDD current. This would suggest that the implementation of an IDDQ testing would increase the fault coverage.…”

“…The basic idea is to switch the Circuit Under Test (CUT) into an oscillator configuration during the test phase, as has been extensively discussed for several circuits (operational amplifiers, filters, data converters) [1][2][3]. During the test, a feedback loop is created to the CUT to produce self-sustained oscillations.…”

Oscillation-based Test Method for Continuous-time OTA-C Filters

“…9.3 9.1C2 (3) Above equation shows that the quality factor Q can be tuned independently without affecting the cut-off frequency co0 of the filter.…”

Oscillation-based DFT for second-order OTA-C filters

“…The DFT of analog circuits can be generally divided into two categories; the first deals with controllability and observability of the internal nodes and the second is to convert the circuit under test (CUT) function and generate an output signal which contains the CUT performance to determine its malfunction. Oscillation-based test (OBT) procedures for analog circuits, based on transformation of the CUT into an oscillator have been recently introduced [3,4]. The oscillation-based DFT structure uses vectorless output frequency comparison between fault-free and faulty circuits and consequently reduces test time, cost, complexity and area overhead.…”

“…The quadrature oscillator model can ideally be described by a second-order characteristic equation as: The oscillation frequency 0 can be obtained by first substituting s = j into equation (1) and considering real and imaginary parts separately. The oscillation conditions are obtained from the Barkhausen criterion [3]. Fig.1.…”