Modified Bisection Search for Faster Metastability Characterization

Circuit state bisection is a robust technique to characterize the performance of multi-stage synchronizers. The passage of metastability between synchronizer stages introduces effects that are not captured by small-signal models and thus numerical integration remains the most reliable method for characterizing this behavior. However, the large number of transient simulations required to characterize one circuit through bisection makes it very difficult to use this technique to run variability analysis or parametric optimization on synchronizer circuits. We present a modified bisection search algorithm that performs 2.5 to 3.2 times faster than conventional bisection without any loss of accuracy. Our method is not restricted to any latch topology or behavior and can safely replace conventional bisection for characterizing any synchronizer circuit.