Memory module with timing-controlled data paths in distributed data buffers

What is this patent about?

’608 is related to the field of high-density memory modules, specifically multi-rank systems where a memory controller manages data across multiple groups of memory devices. In these environments, maintaining signal integrity and precise timing is difficult because physical trace lengths and electrical loads vary across the module. Traditional leveling mechanisms often fail as operating speeds increase, leading to synchronization errors between the controller and the individual memory ranks.

The underlying idea behind ’608 is to decouple the memory controller from the memory devices by using distributed buffer circuits that act as intelligent intermediaries. Instead of the controller driving the entire memory load directly, it communicates with a module control device that distributes commands to these localized buffers. The key insight is to shift the responsibility for timing and signal alignment from the central controller to these buffers, allowing for localized synchronization and load reduction that makes the module appear as a single, manageable load to the system.

The claims of ’608 focus on a memory module architecture featuring a module control device and a plurality of buffer circuits positioned between the memory bus and the memory devices. Each buffer circuit contains a dedicated command processing circuit that decodes control signals to manage individual data paths. Crucially, these data paths incorporate tristate buffers for isolation and delay circuits that dynamically adjust signal timing based on the decoded module control signals, ensuring that data and strobe signals are perfectly aligned regardless of their physical position on the board.

In practice, the module control device receives system commands and translates them into internal module signals and a module clock. The buffer circuits use these signals to selectively enable specific subgroups of memory devices, effectively hiding complex multi-rank configurations from the controller. By utilizing the delay circuit within each data path, the buffer can compensate for propagation delays that occur as signals travel across the module board, ensuring that read and write data meet the strict latency requirements of the system.

This approach differs from prior solutions by eliminating the need for perfectly balanced trace lengths, which often compromise performance and complicate PCB design. By integrating command processing directly into the distributed buffers, the invention allows for real-time adjustment of signal phases and timing. This localized control mitigates metastability issues and allows the memory module to support a higher number of ranks and higher clock frequencies than the memory controller could otherwise support through direct signaling.