Adjustable Pull-Up Resistor Drive Circuit for DRAM Impedance Matching
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Solution Overview
Problem
The existing Dynamic Random Access Memory (DRAM) drive circuits face challenges in maintaining impedance matching between the DRAM chip and the DRAM controller chip, which affects the speed, integrity, and accuracy of data reading and writing, particularly due to deviations in resistance values of pull-up resistors and output impedance.
Innovation Solution
A drive circuit with adjustable pull-up resistors, a pre-drive module, and a resistance value selection circuit that adjusts resistance values based on read or write states to ensure impedance matching by selecting appropriate resistance values for pull-up resistors, using a drive control signal and selection signals to optimize signal transmission during data reading and writing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the resistance value of pull-up resistors in the drive circuit is fixed, then the circuit structure is simple, but the impedance matching between DRAM chip and DRAM controller chip cannot be optimized for different operating conditions
Solution Approach 1:
The patent implements dynamic resistance value adjustment by replacing fixed pull-up resistors with adjustable resistors controlled by control signals. The drive circuit can dynamically change resistance values based on operating conditions (read/write modes, different data rates) to optimize impedance matching, transforming a static circuit into a dynamic one that adapts to varying requirements.
Solution Approach 2:
The patent changes the resistance parameter of the pull-up resistors from fixed to variable. By controlling the resistance values of pull-up resistors through control signals, the circuit can adjust impedance characteristics to match different operating conditions, thereby improving signal transmission quality without requiring complete circuit redesign.
2Manufacturing precision
If the resistance value of pull-up resistors is adjusted to optimize signal transmission, then the speed and accuracy of data reading and writing improve, but the circuit complexity increases
Solution Approach 1:
The patent adjusts the resistance parameter of pull-up resistors to optimize signal transmission characteristics. By controlling resistance values within specific ranges, the circuit achieves better impedance matching and signal integrity, directly improving manufacturing precision in terms of signal transmission accuracy.
Solution Approach 2:
The drive circuit uses dynamic control signals to adjust resistance values in real-time based on operating conditions. This dynamic adjustment capability allows the circuit to maintain optimal signal transmission accuracy across different data rates and modes while managing complexity through integrated control logic.
3Reliability
If different resistance values are used for different operating modes, then the signal integrity improves, but the control complexity increases
Solution Approach 1:
The patent implements control mechanisms that adjust resistance values based on operating modes (read/write, different data rates). The control circuit receives mode information and automatically selects appropriate resistance values, creating a feedback loop that maintains signal integrity without requiring manual intervention or complex external control.
Solution Approach 2:
The drive circuit is designed with multi-functional capability to handle different operating modes using a unified control structure. The same drive circuit can serve multiple functions (different data rates, read/write modes) by dynamically adjusting resistance values, eliminating the need for separate circuits for each mode and simplifying overall control.
Data Source
AI summary
Provided is a drive circuit, including drive units, a pre-drive module, and a resistance value selection circuit. Pull-up resistors of the drive units are adjustable; the pre-drive module is connected to M drive units and controls the pull-up resistors of the M drive units and resistance values of the pull-up resistors through a drive control signal, the M being an integer greater than 1; the resistance value selection circuit is connected to the pre-drive module and configured to select one of a first code and a second code for outputting as a target code according to a selection signal; and the pre-drive module outputs the drive control signal according to the target code.