DDR Memory Termination Circuit Using DC Balance Voltage Control
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Solution Overview
Problem
Conventional termination circuits for DDR3 SDRAMs require a separate termination voltage regulator, increasing manufacturing costs and complexity.
Innovation Solution
A termination circuit comprising drivers, resistors, and capacitors, where a controller adjusts the termination voltage by providing DC balance codes during idle cycles to maintain signal integrity without a separate voltage regulator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a separate termination voltage regulator is used, then precise termination voltage is provided, but manufacturing cost increases
Solution Approach 1:
The patent combines the termination voltage regulation function with the existing driver circuit by integrating a capacitor at the driver output. This eliminates the need for a separate termination voltage regulator, reducing component count and manufacturing cost while maintaining precise termination voltage through the capacitor's ability to store and release charge, stabilizing the voltage at the common node.
Solution Approach 2:
The driver circuit is enhanced to serve dual functions: signal driving and termination voltage regulation. By adding the capacitor to the driver output, the driver becomes a multi-functional component that both drives the transmission line and maintains the termination voltage, eliminating the need for dedicated regulation hardware.
2Reliability
If a separate termination voltage regulator is used, then termination voltage is regulated, but device complexity increases
Solution Approach 1:
The termination voltage regulation function is merged into the driver circuit through the addition of a capacitor. This integration reduces the number of separate components and interconnections, simplifying the overall circuit architecture while maintaining reliable signal integrity through proper termination at the common node.
Solution Approach 2:
The capacitor at the driver output automatically regulates the termination voltage by storing and releasing charge as needed, without requiring external control or additional regulation circuitry. This self-regulating mechanism maintains signal integrity while keeping the circuit simple.
3Measurement precision
If DC balance codes are inserted, then termination voltage is adjusted, but transmission time increases
Solution Approach 1:
The capacitor is pre-charged to the appropriate voltage level before data transmission begins. This preliminary charging action ensures that the termination voltage is already accurate when data transmission starts, eliminating the need for time-consuming DC balance code insertion during operation and maintaining both voltage accuracy and transmission speed.
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
Reduces manufacturing costs and maintains signal integrity by dynamically adjusting termination voltage, eliminating the need for a separate regulator.
Implementation Method 1
Each of the capacitors is coupled between the corresponding resistor and a reference voltage
Data Source
AI summary
A termination circuit for a plurality of memories controlled by a controller is provided. The termination circuit includes a plurality of drivers, a plurality of resistors and a plurality of capacitors. Each of the drivers is coupled to the memories via a transmission line. Each of the resistors is coupled to the corresponding driver via the corresponding transmission line. Each of the capacitors is coupled between the corresponding resistor and a reference voltage. The controller is coupled to the memories via the drivers, and the controller provides a specific code to one of the drivers when a quantity of logic “0” and a quantity of logic “1” transmitted to the memories via the transmission line corresponding to the one of the drivers are unbalanced, so as to adjust a termination voltage of the capacitor corresponding to the one of the drivers.