On-Die Termination Circuit With Coarse-Fine Resistance Tuning
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Solution Overview
Problem
Conventional on-die termination circuits face challenges in achieving high resolution without increasing chip or layout size, leading to errors and malfunctions during high-frequency operations due to reduced pull-up and pull-down resistance accuracy.
Innovation Solution
The implementation of a control mechanism that generates both coarse and fine code signals to adjust termination resistances, utilizing passive and active resistance groups with MOS transistors and resistors to achieve precise resistance levels corresponding to input resistances, thereby enhancing resolution without enlarging the chip area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of code signal bits is increased to improve resolution, then the pull-up and pull-down resistance accuracy is improved, but the chip area and layout size are enlarged
Solution Approach 1:
The code signal generation is segmented into two independent units: a coarse code signal generating unit and a fine code signal generating unit. The coarse unit handles the most significant bits while the fine unit handles the least significant bits, allowing parallel generation of all code bits without requiring additional area for sequential generation circuits.
Solution Approach 2:
The patent transitions from a single-dimensional sequential code generation approach to a two-dimensional parallel approach by simultaneously generating coarse and fine code signals through separate but coordinated units, effectively doubling the information throughput without increasing the critical path delay.
2Device complexity
If conventional single code signal generation is used, then the device area is minimized, but the resolution and resistance control precision are insufficient for high-frequency operations
Solution Approach 1:
The code signal generating means is divided into a coarse code signal generating unit and a fine code signal generating unit, each handling different bit positions. This segmentation allows parallel generation of multiple code bits, improving resolution without proportionally increasing circuit complexity.
Solution Approach 2:
The patent implements dynamic control of the termination resistance by using multiple control signals (coarse code and fine code) that can be independently adjusted. This dynamic control mechanism allows the resistance to be precisely tuned to match the input impedance, enabling high-frequency operation with minimal reflection.
3Reliability
If high-resolution termination control is implemented, then the high-frequency operation stability is improved, but the code signal generation complexity increases
Solution Approach 1:
The code signal generation is divided into coarse and fine segments that can be independently controlled and adjusted. This segmentation reduces the complexity of any single control unit while achieving high-resolution termination control through their combined action, improving high-frequency stability without excessive complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach supports high-resolution on-die termination without increasing device area, ensuring stable high-frequency operation by finely controlling termination resistances through a combination of coarse and fine code signal adjustments.
Implementation Method 1
an on-die termination circuit includes at least one passive resistance group, which has a plurality of units each having a MOS transistor and a resistor, for controlling resistance coarsely in response to a first code signal
Data Source
AI summary
An on-die termination circuit is capable of increasing a resolution without enlargement of a chip or a layout size. The on-die termination circuit includes a control means, a termination resistance supply means, a code signal generating means. The control means sequentially generates a plurality of control signals in a response to a driving signal. The termination resistance supply means supplies a termination resistance in response to a coarse code signal having a plurality of bits and a fine code signal having a plurality of bits. The code signal generating means controls the fine code signal and the coarse code signal in response to the plurality of the control signals in order that the termination resistance has a level which is correspondent to an input resistance.