US Patent 7227385 Actuation circuit for MEMS structures

An actuation circuit which actuates force electrodes using an open loop transconductance stage. The actuation circuit includes at least a first output and a second output, and a first input. The circuit includes a current sink coupled to the first output which is enabled when a current is applied to said first input. The circuit also includes a decision switch which is coupled to the current sink and which enables a current path from the first input to the second output when a voltage present at said first output reaches a predetermined minimum level.