Memory Power Control via Sideband Channel Segmentation
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Solution Overview
Problem
Existing memory device power management systems are inefficient and time-consuming due to the need to wake up the memory device to a higher power state before transitioning to a lower power state, and they lose direct control over the memory device during power state transitions, leading to increased latency and responsiveness issues.
Innovation Solution
Incorporating a sideband channel in the memory bus that allows for direct communication between the host-side memory controller and the power management controller, enabling more extensive control over power management and allowing the memory device to transition to lower power states without waking up to the highest power state, using signal lines for both nominal operations and power management communications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the memory device wakes up to the highest power state before transitioning to a lower power state, then the memory device can be controlled by the host-side memory controller, but the power management becomes inefficient and time-consuming with increased latency
Solution Approach 1:
The patent segments the memory bus into separate channels: a nominal channel for data transfer and a sideband channel for power management control. This allows independent operation of control signals, enabling the host to send power state transition commands without requiring the memory device to wake to full operational state first, thus reducing transition time while maintaining control reliability.
Solution Approach 2:
The sideband channel acts as an intermediary communication path between the host-side memory controller and the power management controller in the memory device. This intermediary channel enables direct power state control without requiring the memory device to fully wake up, resolving the contradiction between maintaining control and reducing transition time.
2Productivity
If the memory device transitions directly to lower power states without waking up, then power management efficiency improves, but the host loses direct control over the memory device during transitions
Solution Approach 1:
By separating the control function into a dedicated sideband channel, the patent enables the host to maintain direct control over power state transitions even when the memory device operates in low-power modes. The segmented architecture ensures control signals can be sent independently of data transfer operations.
Solution Approach 2:
The sideband channel provides a feedback mechanism where the host can send control commands and receive status information about power state transitions. This feedback loop maintains control responsiveness while allowing efficient direct transitions to lower power states without requiring full wake-up cycles.
3Ease of operation
If a separate power management control channel is added to the memory bus, then direct control over power states is enabled, but the device complexity increases
Solution Approach 1:
The sideband channel is designed to serve multiple functions: it carries power management control signals, enables direct host control during low-power states, and provides feedback mechanisms. By making this channel multi-functional, the patent reduces the need for additional separate control circuits, thereby limiting the increase in device complexity while enhancing power control capability.
Data Source
AI summary
A method is described that includes choosing between one of two different ways to cause a memory device to enter a specific one of multiple lower power states that each comprise lower power consumption than a highest low power state. The method also includes asserting a first signal on a first signal line that is coupled to a power management controller of the memory device to indicate to the power management controller that a sideband channel of a memory bus that is coupled to the memory device is activated. The method also includes causing the memory device to enter the specific one of the multiple lower power states by also performing the chosen one of a) sending an in-band signal on said memory bus coupled with said asserting of said first signal, said in-band signal specifying the specific one of the multiple lower power states; or, b) sending a second signal on a second signal line that identifies the specific one of the multiple lower power states.