Lockout Circuit for Memory Command Separation
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Solution Overview
Problem
In memory systems, the inability to properly separate read and write commands when they are closely timed results in truncated signals and glitches, impacting layout and power efficiency, especially in systems with tight timing specifications.
Innovation Solution
A lockout circuit is introduced to prevent truncation of read commands by giving them priority over write commands, using a combined command path that shifts signals from the system clock domain to the DLL domain, and employing a counter circuit to manage timing and prevent premature switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a combined command line is used to carry both read and write commands, then layout area and power consumption are reduced, but the ability to properly separate read and write commands is lost when they are closely timed
Solution Approach 1:
A lockout circuit is introduced as an intermediary component between the combined command line and the command separation logic. This lockout circuit receives the combined read/write commands and uses a read lockout signal to prevent premature switching, ensuring that read commands are fully processed before write commands are accepted. This intermediary mechanism resolves the contradiction by enabling reliable command separation in the combined command line architecture without requiring separate physical command paths.
2Use of energy by moving object
If read and write commands are extended over multiple clock cycles, then power requirements are reduced, but timing separation between commands becomes more difficult
Solution Approach 1:
The system employs feedback mechanisms through the lockout circuit that monitors the state of command processing and dynamically controls the acceptance of new commands. The read lockout signal provides feedback about the current command processing state, enabling the system to maintain proper timing separation even when commands are extended over multiple clock cycles. This feedback control ensures that power-efficient extended commands do not compromise timing separation.
3Productivity
If tight timing specifications are imposed on memory systems, then system performance is improved, but the ability to properly separate commands is compromised
Solution Approach 1:
The lockout circuit implements preliminary action by proactively blocking the write command path when a read command is detected, before the read command is fully processed. This preemptive lockout mechanism ensures that even under tight timing specifications, the system maintains reliable command separation by preventing potential conflicts before they can occur, thereby preserving both high performance and accurate command identification.
Data Source
AI summary
Apparatuses, memories, and methods for facilitating splitting of internal commands using a shared signal path are described. In an example shared signal path, a command circuit is configured to receive a command and an indicator signal. A lockout circuit is coupled to the command circuit and configured to give precedence to a chosen command type by masking the indicator signal. In another example, a counter circuit is coupled to the lockout circuit and configured to force the lockout circuit to sample the indicator signal at regular intervals.