On-Die Termination Circuit with Staggered Switching for Voltage Stability
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Solution Overview
Problem
Conventional on-die termination (ODT) circuits in DRAM modules cause unstable voltage levels in in-chip power supply and ground nodes due to package inductance, leading to signal distortion and operational issues.
Innovation Solution
An ODT circuit with a time-divisional switching mechanism, where multiple switch circuits are controlled by logic to turn on at different timings, reducing the instantaneous current surge and thereby stabilizing the in-chip power supply and ground nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ODT is turned on simultaneously to provide impedance matching and reduce signal distortion, then the signal quality is improved, but the voltage of in-chip power supply node or ground node becomes unstable due to package inductance
Solution Approach 1:
The ODT circuit is divided into multiple independent ODT units (first ODT, second ODT, third ODT, fourth ODT) that can be controlled separately. Each ODT unit is associated with its own switch circuit, allowing the termination function to be segmented across multiple components rather than activated simultaneously by a single ODT, thereby reducing the instantaneous current surge that causes voltage instability.
Solution Approach 2:
The switch circuits are controlled to turn on at different timings through sequentially generated control signals. This periodic or sequential activation of ODT units distributes the current draw over time rather than concentrating it in a single instant, reducing the di/dt effect that interacts with package inductance to cause voltage ripples and instability.
2Stability of the object's composition
If the ODT is turned on first before data transfer to maintain voltage levels at DQ/DQS pins, then the signal level stability is improved, but the instantaneous current surge causes voltage ripple in power supply and ground nodes
Solution Approach 1:
The ODT function is segmented into multiple units that can be activated independently. Instead of one large ODT causing a single large current surge, multiple smaller ODT units are activated separately, each contributing a smaller current that collectively achieves the same impedance matching effect without the harmful voltage ripple.
Solution Approach 2:
The switch circuits are controlled to activate the ODT units at different timings before and during data transfer operations. This preliminary and staggered activation ensures that impedance matching is established while distributing the current surge over time, preventing the concentration of harmful effects at a single moment.
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 reduces voltage ripples and maintains a constant voltage during data transfer, improving the stability and efficiency of memory operations by minimizing latency and power consumption.
Implementation Method 1
The ODT control logic is configured to output the first control signal and the second control signal to control the first switch circuit and the second switch circuit to be turned on at different timings
Implementation Method 2
since a package power supply inductance exists between an external power supply node and the in-chip power supply node, and a package grounding inductance exists between an external ground node and the in-chip ground node
Data Source
AI summary
An ODT circuit is connected to a memory module and includes a first transmission line, a first ODT, a second ODT, a first switch circuit, a third ODT, a fourth ODT, a second switch circuit, and an ODT control logic. The first and second ODTs are coupled to a first node on the first transmission line. The first switch circuit includes a first switch and a second switch, and is driven according to the first control signal. The third and the fourth ODTs are coupled to a second node on the first transmission line. The second switch circuit includes a third switch and a fourth switch, and is driven according to the second control signal. The ODT control logic outputs the first control signal and the second control signal to control the first switch circuit and the second switch circuit to be turned on at different timings.