Metastable compensation circuitry 700 for detecting and compensating for metastable states of a regenerative latch 209 in a charge redistribution analog to digital converter 201. During the operation of the IC, each particular configurable circuit performs a particular operation that is specified by a particular configuration data set for the particular configurable circuit. Also, this approach uses signal and noise current metrics in modeling the parameters of the active device elements. A coupling element such as a sleeve is provided that serves to receive an optical waveguide that is to be oriented in relation to the optical unit. The exhaust port exhaust end is recessed from the suction port fluid entrance end and the two ports are located with respect to one another so that fluid flow from the exhaust port will be effectively drawn into the suction port. The fourth radial direction is angularly spaced between the first and second radial directions and is generally opposite the third radial direction.