Data Output Strobe Circuit With Duty Cycle Correction
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Solution Overview
Problem
Semiconductor memory apparatuses face challenges in generating a data output strobe signal with a correct enable period due to varying duty ratios of rising and falling clocks, leading to unreliable data output operations.
Innovation Solution
A data output strobe signal generating circuit that includes a duty cycle correcting unit to adjust the duty cycle of input clocks, a data output strobe signal generating unit to produce a corrected strobe signal, and a duty cycle control unit to ensure a 50:50 duty ratio, thereby ensuring accurate timing for data output operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the data output strobe signal is generated from rising clock and falling clock with varying duty ratios, then the circuit can operate with simple structure, but the enable period of the data output strobe signal varies making it difficult to control the data output buffer operation
Solution Approach 1:
The duty cycle correcting unit performs preliminary correction on the rising clock and falling clock before they are used to generate the data output strobe signal. By adjusting the duty cycles of the input clocks in advance, the patent ensures that the subsequent strobe signal generation produces the correct enable period, preventing timing errors before they occur.
Solution Approach 2:
The duty cycle correcting unit acts as an intermediary component between the clock generation stage and the strobe signal generation stage. It receives the rising and falling clocks, corrects their duty cycles, and outputs corrected clocks to the strobe signal generating unit, thereby mediating the timing relationship between different parts of the circuit.
2Ease of operation
If the duty ratio of rising clock and falling clock is not 50:50 due to resistance and noise on clock transmitting line, then the clock signal can be transmitted through the line, but the data output strobe signal cannot be generated with correct enable period
Solution Approach 1:
The patent acknowledges that resistance and noise on the clock transmitting line cause duty ratio distortion, but instead of trying to eliminate these physical phenomena, it converts the harmful effect into a manageable parameter. The duty cycle correcting unit is designed to detect and correct the distorted duty ratios, turning the previously harmful distortion into a correctable condition that restores reliable operation.
Solution Approach 2:
The duty cycle correcting unit incorporates feedback mechanisms to detect the actual duty ratios of the rising and falling clocks and adjust them accordingly. By continuously monitoring and correcting the duty cycles based on feedback from the actual signal conditions, the system maintains reliable data output operation despite variations in transmission line characteristics.
Data Source
AI summary
A data output strobe signal generating circuit includes a duty cycle correcting unit that corrects the duty ratio of an input clock in response to a control signal to generate a corrected clock. A data output strobe signal generating unit receives the corrected clock and generates a data output strobe signal. A duty cycle control unit receives the data output strobe signal and outputs the control signal.