Memory Output Driver Slew Control for Termination Matching
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Solution Overview
Problem
Conventional semiconductor memory devices do not adequately adjust the slew rate of the output driver circuit in response to changes in termination resistance, leading to potential errors in signal integrity (SI).
Innovation Solution
An output driver circuit that adjusts its slew rate based on termination resistance setting information, using a pre-driver to generate control signals and pull-up/pull-down drivers to output data at appropriate levels, with the number of inverters determining the slew rate in proportion to or inversely proportional to the termination resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the termination resistance is adjusted according to system conditions, then the adaptability is improved, but the signal integrity deteriorates due to inadequate slew rate adjustment
Solution Approach 1:
The patent implements dynamic adjustment of both termination resistance and slew rate based on system conditions. The output driver circuit dynamically changes the slew rate in response to termination resistance settings, enabling the system to adapt to different loading conditions (single DIMM, double DIMM, etc.) while maintaining signal integrity through coordinated parameter adjustment.
Solution Approach 2:
The patent changes multiple parameters simultaneously - termination resistance and slew rate - to optimize performance under different system conditions. By adjusting the slew rate parameter in conjunction with termination resistance, the circuit maintains proper signal characteristics across varying load conditions, resolving the contradiction between adaptability and signal integrity.
2Productivity
If the slew rate is increased to improve data output speed, then the productivity is improved, but the signal integrity deteriorates due to excessive transition speed
Solution Approach 1:
The slew rate is dynamically adjusted based on system conditions rather than being fixed. The circuit can increase slew rate when needed for faster data output (improving productivity) while decreasing it when signal integrity is at risk, achieving optimal balance between speed and reliability through conditional adjustment.
Solution Approach 2:
The patent adjusts the slew rate parameter to optimal values based on termination resistance settings and system conditions. By changing this parameter appropriately, the circuit achieves fast data output when conditions permit while maintaining signal integrity when required, resolving the contradiction between productivity and reliability.
Data Source
AI summary
Output driver circuit, semiconductor memory device including the output driver circuit, and method for operating the semiconductor memory device, including a pre-driver to generate a pull-up control signal and a pull-down control signal according to a logic value of data to output, and to adjust and output a slew rate of the pull-up control signal and a slew rate of the pull-down control signal according to a termination resistance setting information, a pull-up driver to output logic high data in response to the pull-up control signal and a pull-down driver to output logic low data in response to the pull-down control signal.