Device Design Guidelines: Agilex™ 5 FPGAs and SoCs

ID 813741
Date 4/01/2024
Public
Document Table of Contents

5.3.2.3. I/O Termination

Table 41.  I/O Termination Checklist

Number

Done?

Checklist Item

1

 

Check I/O termination and impedance matching for chosen I/O standards, especially for voltage-referenced standards.

Voltage-referenced I/O standards require both a VREF and a termination voltage (VTT). The reference voltage of the receiving device tracks the termination voltage of the transmitting device. Each voltage-referenced I/O standard requires a unique termination setup.

Although single-ended, non-voltage-referenced I/O standards do not require termination, impedance matching is necessary to reduce reflections and improve signal integrity.

Agilex™ 5 on-chip series and parallel termination provides the convenience of no external components. Alternatively, you can use external pull-up resistors to terminate the voltage-referenced I/O standards such as SSTL and HSTL.

Differential I/O standards typically require a termination resistor between the two signals at the receiver. The on-chip differential resistor is supported whether 1.05 V, 1.1 V, 1.2 V, or 1.3 V is used for true differential signaling.