Supporting Line Rates up to 9,830.4 Mb/s - 8.12 English

CPRI LogiCORE IP Product Guide (PG056)

Document ID
PG056
Release Date
2024-12-13
Version
8.12 English

If the CPLL in the UltraScale device supports line rates over 9,830.4 Mb/s then the CPLL is used at this line rate. The clocking for 9,830.4 Mb/s capable cores is the same as that shown in Figure 1.

The following figure shows the clock configuration for a core on an UltraScale architecture supporting 9,830.4 Mb/s where the CPLL does not support speeds of 9,830.4 Mb/s. In master mode, the reference clock is generated from a crystal oscillator. In slave mode the reference clock is generated from the recovered clock using an external jitter removal PLL.

Figure 1. Core Clock Configuration at 9,830.4 Mb/s (UltraScale Architecture) Generated by Your Tool

At line rates up to and including 6,144.0 Mb/s, the channel PLL is used. The quad PLL is used at 9,830.4 Mb/s. The quad PLL is set up to provide a 4,915.2 MHz PLL clock to the transceiver. The core can use either QPLL0 or QPLL1 from the GTHE3/GTYE3_COMMON block. The qpll_select input to the core should be tied Low when using QPLL0 and High when using QPLL1.

In slave cores, rather than routing the recovered clock directly to the external jitter-removal PLL as shown in the preceding figure, the recovered clock can be prescaled within the device to a constant nominal rate of 15.36 MHz for all line rates.The example design supplied with the core contains an example implementation of this prescaling technique.

Note: For slave cores the external jitter-removal PLL must free-run in the absence of a reference signal; a PLL that turns off in the absence of a reference causes the transceiver to fail to start up. Contact your local System I/O specialist for guidance in selecting a PLL for your application.