DDR3 Termination Impedance Control for Dynamic ODT Timing
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Solution Overview
Problem
Conventional ODT control circuits for DDR3 semiconductor memory devices lack the ability to dynamically control termination impedance, which is essential for maintaining signal integrity due to factors like aging and temperature variations, and do not support the dynamic ODT operation as required by JEDEC specifications.
Innovation Solution
A termination impedance control circuit that includes a counter unit to generate codes based on external and internal clocks, a dynamic controller to enable and disable dynamic termination operations based on these codes, and a storage unit to manage the termination operation timing according to burst length, ensuring precise control of the dynamic ODT mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fixed resistance is applied to the termination of the devices to match the impedance, then the impedance matching may be properly achieved initially, but the impedance matching deteriorates due to aging of integrated circuits, temperature variation, and manufacturing processes
Solution Approach 1:
The patent implements dynamic ODT operation by enabling the termination resistance to change over time based on operational conditions. The system transitions from static fixed resistance to dynamic adjustable resistance, allowing the termination impedance to adapt to aging effects, temperature variations, and manufacturing process deviations, thereby maintaining reliable impedance matching throughout the device lifecycle
Solution Approach 2:
The patent changes the resistance parameter dynamically by adjusting the number of turn-on transistors connected in parallel. This parameter adjustment mechanism allows the termination resistance to be modified based on operational conditions, enabling the system to compensate for environmental changes and maintain impedance matching without requiring fixed resistance values
2Adaptability or versatility
If the ODT control circuit controls the start and end modes of the dynamic ODT operation according to data input/output, then the dynamic ODT operation can be properly supported for DDR3-level devices, but the device complexity increases
Solution Approach 1:
The patent segments the ODT control functionality into distinct start and end mode control operations. By dividing the dynamic ODT operation into separate enable and disable control sequences, the system can implement complex DDR3-level dynamic termination support while managing circuit complexity through modular functional segmentation
Solution Approach 2:
The patent creates a universal ODT control circuit that handles both start and end modes of dynamic operation, as well as data input and output operations. This multi-functional control circuit consolidates multiple control functions into a single integrated unit, reducing overall device complexity while supporting comprehensive dynamic ODT operations required for DDR3-level devices
Data Source
AI summary
A termination impedance control circuit is capable of controlling a dynamic ODT operation in a DDR3-level semiconductor memory device. The termination impedance control circuit includes a counter unit configured to count an external clock and an internal clock to output a first code and a second code, respectively, and a dynamic controller configured to enable a dynamic termination operation by comparing the first code with the second code in response to a write command and disable the dynamic termination operation after a predetermined time, determined according to a burst length, has lapsed after the dynamic termination operation is enabled.