Patent ID: 8346832

Claim:
A circuit for generating a random output value, comprising: a bistable circuit having two stable states in which a 0 or a 1 is output and having a balanced metastable state in which a floating value between 0 and 1 is output, said bistable circuit resolving from said metastable state to one of said stable states on being switched on, attainment of said metastable state depending on a voltage level at a port on said bistable circuit; a voltage level control circuit for controlling a voltage level at said port on said bistable circuit; a time measuring circuit for measuring a switching time taken for said bistable circuit to switch from said metastable state to one of said stable states following switch on; and control logic for controlling said time measuring circuit, said voltage level control circuit and a switching off and on of said bistable circuit, said control logic being adapted to perform a following sequence: control said voltage level control circuit to set a predetermined voltage level at said port on said bistable circuit, switch said bistable circuit on, detect a measured switching time, and turn said bistable circuit off and if said measured switching time is longer than a predetermined value, output said resolved stable state of said bistable circuit as said random output value; wherein said control logic is adapted to perform a resetting operation including performing said sequence a plurality of times for different set voltage levels at said port on said bistable circuit and not outputting said resolved stable states during said resetting operation, and following said resetting operation, said control logic is adapted to reset said predetermined voltage level to a voltage level value outputting a longest mean switching time during said resetting operation.