Metastability of a Flip-flop and Its Utilization for a Capacitance Measurement

Activating a flip-flop circuit by a current fast-rising slope impulse, the circuit occupies one of the two stable states, the stable state ‘one‘ or ‘zero‘. In case of a perfect flip-flop symmetry over a large number of cycles, a noise causes the ratio of ‘ones‘ and ‘ zeros‘ is equal to one – 50% position of a flip-flop. However, any imbalance in the system changes the probability of taking a ‘one’ or a ‘zero’, and thus the ratio of ‘ones’ and ‘zeros’. In this paper, the formula for equivalent voltage of the flip-flop circuit is derived. This voltage is incorporated into the flip-flop as a voltage source to restore 50% position. The formula is derived for the first time. The results are useful for capacitance measurement and in capacitive sensor applications.