Memory Interface Power Management via CAL Mode
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Solution Overview
Problem
Memory systems face challenges in reducing power consumption and improving reliability, particularly due to the need for constant activation of command/address input receivers and high power consumption by input termination circuits, which are not efficiently managed in standard control timing modes.
Innovation Solution
Implementing a command-and-address-latency (CAL) mode in memory interface devices that allows for multiple clock cycles of latency between the chip-select and command/address signals, enabling power state management of input receiver and termination circuits, and parity signal checking before re-driving signals to DRAM devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If standard control timing mode is used with concurrent chip-select and command/address signals, then signal transmission speed is maintained, but power consumption increases due to constant activation of input receivers and termination circuits
Solution Approach 1:
The patent implements dynamic power management by transitioning input receiver circuits and termination circuits between active and low-power states based on the timing relationship between chip-select and command/address signals. The CAL mode enables circuits to be in low-power state during the latency period, while standard mode keeps them active for immediate response, allowing the system to dynamically adjust power consumption based on performance requirements.
Solution Approach 2:
The patent introduces periodic activation of input receivers and termination circuits in CAL mode, where these circuits are activated only during specific time windows (when command/address signals are expected) rather than continuously. This periodic action reduces average power consumption while maintaining signal transmission capability when needed.
2Use of energy by moving object
If CAL mode is used to reduce power consumption, then standby current is reduced, but additional latency cycles are introduced between chip-select and command/address signals
Solution Approach 1:
The system dynamically adjusts timing parameters to compensate for CAL mode latency. By programmatically setting timing values in the memory controller and memory device, the additional latency introduced by CAL mode can be accounted for in the overall timing budget, allowing the system to maintain correct operation while benefiting from reduced power consumption.
3Reliability
If input termination circuits are always active to ensure signal integrity, then signal transmission reliability is improved, but power consumption increases
Solution Approach 1:
Input termination circuits are activated periodically only when command/address signals are expected to arrive, rather than being continuously active. This is achieved by synchronizing termination circuit activation with the chip-select signal timing, ensuring signal integrity is maintained during active periods while reducing power consumption during idle periods.
Solution Approach 2:
The termination circuits are activated in advance of the expected command/address signal arrival, triggered by the chip-select signal. This preliminary action ensures that the termination circuits are ready to properly terminate signals when they arrive, maintaining signal integrity without requiring continuous activation.
4Quantity of substance
If multiple memory devices are connected to improve system capacity, then memory capacity increases, but power consumption and signal transmission complexity increase
Solution Approach 1:
The patent segments the memory system into multiple independently controllable memory devices, each with its own chip-select signal. This allows the host controller to activate only the specific memory device(s) needed for current operations, reducing overall power consumption compared to having all devices continuously active, while still providing high total memory capacity through the combined resources of multiple devices.
Data Source
AI summary
A method for operating a memory module device. The method can include transferring a chip select, command, and address information from a host memory controller. The host memory controller can be coupled to a memory interface device, which can be coupled to a memory module. The memory module can comprise a plurality of memory devices. The chip select, command and address information can be received at the memory interface using a command-and-address-latency (CAL) mode. Control logic can be used to initiate a power state transition from a first power state to a second power state of an input termination circuit in the memory interface device.