Cyclone V Device Handbook: Volume 2: Transceivers

ID 683586
Date 10/24/2018
Document Table of Contents

1.2.5. Calibration Block

The calibration block calibrates the differential OCT resistance and analog circuitry in the transceiver PMA to ensure the functionality is independent of PVT.

It is also used for duty cycle calibration of the clock line at serial data rates ≥ 4.9152 Gbps.

There is only one calibration block available for the Cyclone® V transceiver PMA. It is located on the top left of the device (same side as the transceiver channels).

Figure 20. Calibration Block Location and Connections in Cyclone V DevicesTransceivers are on the left side of the device only.

The calibration block internally generates a constant internal reference voltage, independent of PVT variations. The block uses the internal reference voltage and external reference resistor to generate constant reference currents.

Note: You must connect the external reference resistor to the RREF pin.

These reference currents are used by the analog block calibration circuit to calibrate the transceiver banks. You must connect a separate 2 kΩ (tolerance max ± 1%) external resistor on each RREF pin to ground. To ensure the calibration block operates properly, the RREF resistor connection in the board must be free from external noise.