On-Die Termination Circuit for DQ and DQS Impedance Decoupling
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Solution Overview
Problem
Conventional on-die termination circuits require a large number of global lines to support added functions and signal control, leading to increased circuit area and reduced efficiency due to the need for multiple global lines for impedance adjustment and write leveling operations.
Innovation Solution
An on-die termination circuit design that transmits only one type of impedance adjustment signal through global lines, using modulation and local lines for the second impedance adjustment signal, reducing the number of global lines required and allowing for independent impedance control of DQ and DQS pads during write leveling operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple impedance adjustment signals are transmitted through global lines to support various operations (read, write leveling, on-die termination), then the impedance control capability is improved, but the number of global lines increases leading to increased circuit area
Solution Approach 1:
The patent merges multiple impedance adjustment signals (OCDT_DQ, OCDT_DQS, WTLEV) into a single global line by encoding them together. The impedance adjustment unit generates a combined impedance adjustment signal that incorporates information for all three operations, allowing the global line to carry multiple control functions simultaneously rather than requiring separate dedicated lines for each signal.
Solution Approach 2:
The single global line is designed to serve multiple functions by transmitting a unified impedance adjustment signal that can accommodate read operations, write leveling operations, and on-die termination operations. The impedance adjustment unit dynamically configures the signal based on the current operation type, making the global line universal rather than operation-specific.
2Measurement precision
If separate global lines are used for transmitting impedance adjustment signals for DQ and DQS pads, then the impedance adjustment precision is improved, but the device complexity increases
Solution Approach 1:
The patent combines multiple impedance adjustment signals into a single encoded signal transmitted through one global line. The impedance adjustment unit processes multiple control signals (OCDT_DQ, OCDT_DQS, WTLEV) and generates a unified impedance adjustment signal that maintains the precision needed for DQ and DQS pad impedance control while eliminating the need for separate transmission lines.
Solution Approach 2:
The patent changes the parameter representation of impedance adjustment signals by encoding multiple control parameters into a single composite signal. Instead of transmitting separate voltage levels for different operations, the system uses a unified signal format that carries encoded information about the desired impedance state, operation type, and pad configuration, reducing line count while preserving control precision.
Data Source
AI summary
An on-die termination circuit including: a DQS circuit block configured to terminate a DQS pad in response to a first impedance adjustment signal which is transmitted through a global line; and a DQ circuit block configured to terminate a DQ pad in response to a second impedance adjustment signal which is generated by changing the first impedance adjustment signal or a value of the first impedance adjustment signal depending on whether a setup operation proceeds.