Dynamic Output Enable Signal Generation Circuit for Clock Skew
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Solution Overview
Problem
Conventional semiconductor memory devices face issues with accurate output enable signal generation due to skew between external and internal clock signals, leading to undesired timing consequences when the frequency of the external clock signal changes, as the existing OE signal generation circuits fail to adjust the count value N accordingly.
Innovation Solution
The proposed output enable signal generation circuit includes an OE reset signal generation unit, a delay unit, a counter unit, and an OE signal output unit that adjust the count value N in response to changes in the external clock signal frequency, ensuring synchronization with the DLL clock signal and minimizing timing errors by resetting the count value N when the frequency changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the OE signal generation circuit uses a fixed count value N based on external clock signal, then the circuit structure is simple, but timing accuracy deteriorates when external clock frequency changes
Solution Approach 1:
The count value N is changed from a fixed parameter to a dynamic parameter that automatically adjusts according to the external clock signal frequency. The circuit detects frequency changes and resets/counters clock cycles to determine the appropriate N value, making the system adaptive rather than static.
Solution Approach 2:
The circuit incorporates a feedback mechanism where the output enable signal generation is monitored and adjusted based on the actual external clock frequency. The frequency detection unit continuously monitors the clock signal and provides feedback to adjust the count value N, ensuring timing accuracy is maintained despite frequency variations.
2Measurement precision
If the OE signal generation circuit adjusts the count value N in response to external clock frequency changes, then timing accuracy is improved, but the circuit complexity increases
Solution Approach 1:
A frequency detection unit and control logic are introduced as intermediary components between the external clock signal and the OE signal generation circuit. These intermediaries automatically handle the frequency measurement and count value adjustment, isolating the complexity from the main OE generation function while maintaining timing accuracy.
Solution Approach 2:
The OE signal generation circuit performs its own frequency detection and automatic adjustment of the count value N without requiring external intervention or complex external control systems. The circuit monitors its own operating conditions and self-corrects to maintain timing accuracy.
Data Source
AI summary
An output enable signal generation circuit includes an output enable reset signal generation unit configured to enable an output enable reset signal in response to an external clock signal, a DLL locking signal, and a reset signal, an output enable reset signal delay unit configured to delay the output enable reset signal and output the delayed output enable reset signal, a counter unit configured to output the count of the external clock signal as a value in response to the output enable reset signal and the delayed output enable reset signal, a read command delay unit configured to delay a read command and output the delayed read command, and an output enable signal output unit configured to shift the delayed read command in synchronization with a DLL clock signal and output an output enable signal, according to control of CL and the count value.