A METHOD OF SHORTENING METASTABLE OPERATION DURATION TIME BY THE USE OF FEEDBACK

If metastable operation (MS operation) occurs in conflict-resolving ci rcuits, propagation delay time of flip-flop (FF) increases by the amou nt of its duration time and a malfunction may occur. This paper propos es a method of shortening duration time of mu S operation that occurs when two inputs of RSFF consisting of CMOS NAND gates are switched fro m logic 0 to 1 approximately at the same instant. The MS operation is detected and fed back to inputs so that it is forced to terminate. A c onfiguration of RSFF that has feedback based on this idea is first pre sented, and then a principle of shortening MS operation duration time follows. Then, considering implementation of RSFF by n-well process, f eedback connection and MOSFET parameters are optimized. Although hardw are increases slightly by addition of feedback, the result shows the M S operation duration time increase rate against input phase difference (switching time difference of two inputs of RSFF), and the range of i nput phase difference for MS operation incidence are reduced by approx imately 1/4 and 1/3, respectively, compared with conventional methods.