Cyclone® III devices include on-chip series termination (OCT) or driver impedance matching (Rs) for single-ended I/O standards. This feature helps:
- Improve signal integrity by matching impedance
- Lower cost by eliminating the need for external resistors and reducing PCB size
- Simplify PCB layout on space constrained boards
The OCT feature is available on all Cyclone III device I/O banks and can be used with or without calibration (Figure 1). When used with calibration the device calibrates the impedance to external Rup and Rdn precision resistors during device power up.
Figure 1. Using Cyclone III OCT Feature With or Without Calibration
