Semiconductor Memory Device Timing Margin Control
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Solution Overview
Problem
High-speed semiconductor memory devices face delays in internal operations due to differing circuit paths for command and address signal decoding, leading to reduced timing margins and instability under varying operation conditions.
Innovation Solution
A semiconductor memory device with a command decoding circuit, control circuit, and column decoding circuit that activates internal address signals earlier than strobe signals, ensuring sufficient timing margins for data access by synchronizing signals with the system clock and maintaining a 0.5 tCK time lag between internal control signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If command and address signals are decoded through separate circuit paths to enable high-speed operation, then operation speed improves, but timing margin deteriorates due to asynchronous signal arrival
Solution Approach 1:
The patent applies preliminary action by activating the internal address signal before the strobe signal. Specifically, the address signal is activated at a first time point and the strobe signal at a second time point, where the first time point precedes the second time point. This advance activation of the address signal ensures that the decoding circuit is ready to process the strobe signal immediately upon arrival, eliminating waiting time and ensuring sufficient timing margin while maintaining high-speed operation.
2Productivity
If internal operations are performed rapidly to improve data output speed, then productivity improves, but system stability deteriorates due to insufficient timing margin
Solution Approach 1:
The patent implements preliminary action by preparing the address signal in advance before the strobe signal arrives. The address signal is activated at a first time point that is earlier than the second time point when the strobe signal is activated. This advance preparation ensures that all subsequent decoding and data output operations can proceed rapidly without compromising system stability, as the critical path is already prepared and timing margins are sufficient.
3Speed
If command decoding and address decoding are performed in parallel circuits, then operation speed improves, but timing precision deteriorates due to varying signal delays
Solution Approach 1:
The patent resolves the timing precision issue by applying preliminary action to the address signal path. The address signal is activated at a first time point before the strobe signal activation at a second time point. This time offset compensates for the varying delays in parallel circuit paths, ensuring that both signals arrive at the decoding circuit with sufficient and equal timing margins, thereby maintaining timing precision alongside high decoding speed.
Data Source
AI summary
A semiconductor memory device has a timing margin for internal operations. The semiconductor memory device can activate an internal control signal for controlling an external address sooner than an internal control signal for controlling an external command to secure a sufficient time for data access. The semiconductor memory device includes a command decoding circuit configured to decode an external command to output an internal command signal for an internal operation corresponding to the external command, a control circuit configured to generate a strobe signal for controlling the internal operation in response to the internal command signal and an internal address signal by decoding an address signal received from outside such that the internal address signal activates sooner than the strobe signal, and a column decoding circuit configured to generate a data access signal when both the internal address signal and the strobe signal are activated.