Stratix® 10 Clocking and PLL User Guide

ID 683195
Date 4/01/2024
Public
Document Table of Contents

2.1.1.3. Programmable Clock Routing

The Quartus® Prime software automatically configures the clock switch, clock tap, SCLK, and row clock multiplexers to generate skew-balanced clock trees. The resulting routing path distributes the signal from the clock source to all target destinations in one or more clock sectors.

The Quartus® Prime software creates efficiently balanced clock trees of various sizes, ranging from a single clock sector to the entire device, as shown in the following figure. By default, the Quartus® Prime Software automatically determines the size and location of the clock tree. Alternatively, you can directly constrain the clock tree size and location either with a Clock Region assignment or by Logic Lock Regions.

The total insertion delay for the clock network depends on the number of clock resources needed to implement the clock tree, increasing with the number of clock sectors reached and the distance of the furthest clock destination from the signal source. As delay increases, the worst-case skew for crossing clock sectors using different clock tree branches grows, potentially degrading the maximum performance. For very high-speed clock signals, it is advantageous to reduce the number of clock sectors driven, which reduces the clock skew, and to reduce the distance between the clock source and the furthest destination, which reduces both clock skew and total clock insertion delay.

Figure 4. Examples of Clock Networks Sizes Using Stratix® 10 Programmable Clock Routing