A system and method for characterizing process variations are provided. A circuit comprises a plurality of inverters arranged in a sequential loop, and a plurality of transmission gates, with each transmission gate coupled between a pair of serially arranged inverters. Each transmission gate comprises a first field effect transistor (FET) having a first channel, and a second FET having a second channel. The first channel and the second channel are coupled in parallel and a gate terminal of the first FET and a gate terminal of the second FET are coupled to a first control signal and a second control signal, respectively.