Frequency-Independent Parametric Built in Test Solution for PLLs with Low Speed Test Resources

Phase Locked Loops (PLLs) are required to meet analog specifications such as lock time, phase error, jitter in addition to the frequency lock test in production. Parametric testing of PLLs is resource intensive and requires high precision hardware on the Automatic Test Equipment (ATE). This paper proposes a Built in Self Test (BIST) scheme to perform functional and parametric testing using low frequency ATE resources. The BIST module is independent of the PLL frequency and can be used effectively in multi-PLL System-on-a-Chip (SoC) modules. The scheme uses the Phase Detector (PD) output signature to test for lock and transient response using a digital BIST module. The BIST scheme is designed without impacting the mission mode performance by not perturbing analog nodes and the phase sensitive feedback loop. The test methodology enables parametric testing for process variation and specification compliance while using minimal external test resources. Process and operating condition independence is a critical factor to ensure compatibility with volume manufacturing and test environments.