IBUFG和IBUFGDS的輸入端僅僅與芯片的專用全局時鐘輸入管腳有物理連接，與普通IO和其它內(nèi)部CLB等沒有物理連接。

所以，IBUFG輸入的不能直接接另外信號。

GTH transceiver primitives are called GTHE3_COMMON and GTHE3_CHANNEL in
UltraScale FPGAs, and GTHE4_COMMON and GTHE4_CHANNEL in UltraScale+ FPGAs.

Four GTHE3/4_CHANNEL primitives clustered together with one GTHE3/4_COMMON
primitive are called a Quad or Q.

The GTHE3/4_COMMON primitive contains two LC-tank PLLs (QPLL0 and QPLL1). The
GTHE3/4_COMMON only needs to be instantiated when an LC-tank PLL is used in the
application.

refclk進來后要用IBUFDS差轉(zhuǎn)單，然后根據(jù)情況使用QPLL或者CPLL。