第二，一旦系统时钟需要向后调整，那么GENERATE_UNIQUE将可能返回重复的值。
Second, if the system clock is adjusted backwards, GENERATE_UNIQUE will return duplicate values.
设计了一个数字时钟数据恢复电路，采用相位选择锁相环进行相位调整，在不影响系统噪声性能的前提下大大降低了芯片面积。
A phase selection PLL is adopted to adjust the phase of the recovered clock, and the chip area of the recovery circuit is greatly reduced without sacrificing the noise performance of the system.
动态功耗管理是一种系统级低功耗设计技术，降低功耗的思路是根据系统当前负载动态调整时钟频率或者关闭时钟。
Dynamic power Management (DPM) is a technique to reduce power consumption of systems by shutting down clocks or changing their frequency according to system loads.
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