| 摘要 |
One or more timing signals used to time data and command transmission over highspeed data and command signaling links are paused or otherwise disabled when a memory system enters a low-power state, and require substantial time to be re-established at appropriate frequency and/or phase as the system returns to an active operating state. Instead of waiting for the high-speed timing signals to be re-established before beginning memory access operations, an alternative, lower-frequency timing source is used to time transfer of one or more memory-access commands over a combination of data and command signaling links while the high-speed timing signals are being restored, thereby hastening transmission of memory-access commands to memory devices and reducing the incremental latency required to exit the low-power state. A timing signal generators capable of glitchlessly shifting a timing signal between two or more oscillation frequencies may also (or alternatively) be provided, thus enabling different-frequency timing signals to be delivered to system components via the same timing signal paths in either operating state. When the timing signal is used to time data (or command) transfer over information-bearing signaling links, the ability to glitchlessly shift the timing signal frequency enables a corresponding glitchless shift between lower and higher data rates on the information-bearing signaling links. |
