A selection circuit. The selection circuit comprises a logic circuit, an array of sub-circuits and a switching circuit electrically coupled to each other. The selection circuit is subjected to a first operating condition. The switching circuit selects a group of sub-circuits from the array. The selection circuit generates a first frequency. The selection circuit is subjected to a second operating condition that is different from the first operating condition and generates a second frequency. A first frequency differential between the first frequency and the second frequency is compared to a predetermined frequency differential to determine if the first frequency differential is about equal to the predetermined frequency differential.