Encoded On-Die Termination for Read/Write Impedance Switching
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Solution Overview
Problem
Traditional on-die termination (ODT) systems in memory systems rely on binary signals, limiting the ability to change termination values between read and write operations, leading to suboptimal performance and increased power consumption due to the need to use a single termination value for both operations.
Innovation Solution
Implementing serial encoding on the ODT signal line allows for the application of unique read and write termination values by encoding multiple serial bits, enabling independent adjustment of termination impedance for improved signal integrity and reduced power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If binary ODT signaling is used to control termination, then the system is simple to operate, but the ability to change termination values between read and write operations is limited
Solution Approach 1:
The patent applies parameter changes by encoding multiple serial bits on the ODT signal line to represent different termination impedance values. Instead of using a simple binary on/off signal, the system transmits encoded sequences (e.g., '1010' for RTT_NOM, '1110' for RTT_WR) that convey specific termination parameters, enabling dynamic adjustment of termination values for different operations while maintaining signal line reuse
Solution Approach 2:
The ODT signal line is given multi-functionality by using it both as a traditional binary control signal and as an encoded data carrier. The same physical signal line can convey different types of information depending on the encoding scheme used, allowing the system to control multiple termination values without adding separate dedicated control lines for each function
2Adaptability or versatility
If configuration registers are used to change ODT termination values, then different termination values can be set, but channel bandwidth is consumed and performance is penalized
Solution Approach 1:
The patent extracts the termination control information from the main data channel by using a dedicated ODT control signal line. This separates the termination configuration function from the data transfer function, allowing termination values to be changed without consuming宝贵的 channel bandwidth that would otherwise be used for data transmission
Solution Approach 2:
The ODT signal line acts as an intermediary channel that carries control information for termination impedance adjustment. This intermediary mechanism provides a direct control path that bypasses the need to use the main data channel for configuration, enabling efficient termination control independent of data transfer operations
3Ease of operation
If a single termination value is used for both read and write operations, then the system is easier to control, but signal integrity and power efficiency are suboptimal
Solution Approach 1:
The patent applies local quality by assigning different termination impedance values optimized for specific operations: RTT_NOM for read operations and RTT_WR for write operations. Each operation type receives a termination value tailored to its specific signal characteristics and requirements, improving signal integrity for both reads and writes rather than using a compromise single value
4Adaptability or versatility
If traditional ODT signaling is used, then power consumption is reduced with simple control, but the ability to optimize termination for different operations is lost
Solution Approach 1:
The patent introduces dynamics by making the termination impedance adjustable and operation-specific. Instead of a static single termination value, the system dynamically switches between RTT_NOM and RTT_WR based on the operation type (read or write), allowing optimization of power consumption and signal integrity for each operational mode
Data Source
Figure 1A~1B
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AI summary
On-die termination (ODT) is triggered through a serial signal encoding on an ODT signal line instead of a simple binary enable signal. An ODT circuit applies one of multiple termination impedances based on the ODT signal encoding. An ODT enable signal line receives an ODT enable signal as multiple serial bits to encode the selected termination impedance, to cause the ODT circuit to apply the selected termination impedance.