Built-in self-test structure for fault detection of charge-pump phase-locked loop

A defect-oriented built-in self-test (BIST) structure of charge-pump phase-locked loop (CP-PLL) for high fault coverage and low area overhead test solution is proposed. It employs a new structure of phase/frequency detector, a D flip-flop and some existing blocks in the PLL as the input stimulus generator and fault feature extracted devices for testing evaluation. Thus, no extra test stimulus or high-performance measured instruments are required for test. The structure is easily implemented and has a little influence on the performance of CP-PLL. Fault simulation results indicate that the proposed BIST structure has high fault coverage (98.75%) and low area overhead (0.78%).