Clock Oscillator
Note: The clock oscillator is separate from and not synchronous to the clock provided by the USB host interface.
The Artix UltraScale+ Clock Management Tiles (CMTs) are located adjacent to each of the three HP banks available on the SZG-HUB1450. Each CMT contains one MMCM and two PLLs that can be used for various clocking features.
In addition to the USB host interface clock, there is a single, fixed-frequency clock oscillator which provides a general-purpose reference clock to the FPGA fabric.
| CLOCK | FREQUENCY | FPGA Pins (P / N) |
|---|---|---|
| Fabric (including DDR4 SDRAM interface) | 156.25 MHz | K22 / K23 (Bank 66) |
The fabric clock oscillator is attached to global clock (GC) input pins on HP Bank 66. This bank is shared with the DDR4 interface. This clock provides a direct connection to the MMCM used by AMD’s MIG IP within Bank 66. The 156.25-MHz oscillator frequency enables the precise clock frequencies necessary for DDR4-2166.
The LVDS output of the oscillator is AC-coupled and DC-biased according to the recommendations given in Figure 1‐83 of AMD UG571.