U. Kac, F. Novak.
Oscillation Test Scheme of SC Biquad Filters Based on Internal Reconfiguration.
Journal of Electronic Testing: Theory and Applications, Vol. 23, No. 6, 2007, pp. 485-495.
In this paper, we explore general conditions for the
oscillation based test of switched-capacitor biquad filter stages.
Expressions describing the characteristics of a filter stage put
into oscillation are derived and conditions for achieving
oscillation by internal transformation of the filter stage are
explored. Reconfiguration scheme based on the transformation
of the biquad filter stage to a quadratic oscillator is
studied. Theoretically the circuit can be put into oscillation
by de-activating a single capacitor. Simulations, however,
show that in practice a carefully designed low feed-back loop
is required to achieve acceptable oscillation test mode.