PCIe 4.0 PLL Bandwidth Testing

Figure 1: PLL bandwidth testing
ensures that the add-in card's
PLL bandwidth and peaking
are within specifications

The final piece of the PCIe 4.0 compliance-test puzzle—at least until PCI-SIG completes its test definitions—is the PLL bandwidth test. This test, which is performed only on add-in cards, verifies that the PLL bandwidth and peaking are within the limits allowed by the PCIe 4.0 specification (Figure 1).