DDR PHY Transmitter Power Collapse Protection for Thin-Oxide Gates

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Solution Overview

Problem

Transmitter circuits in memory devices are susceptible to electrical overstress (EOS) due to reductions in transistor gate length and gate oxide thickness, which limits their ability to sustain voltage levels required by different memory standards.

Innovation Solution

A transmitter circuit is designed with a first driver circuit that includes a thin-oxide transistor to couple an input/output pad to a first voltage rail, a gate pullup transistor to couple the gate of the thin-oxide transistor to a second voltage rail when a third voltage rail collapses to zero volts, and a switch to block the transmission of a gating signal to the thin-oxide transistor during voltage collapse.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If reductions in transistor gate length and gate oxide thickness are implemented to increase transistor density, then transistor density is improved, but susceptibility to electrical overstress increases

Engineering Contradiction:

Improvetransistor densityVSAvoidelectrical overstress susceptibility

Core Design Contradiction:

Quantity of substanceVSObject-affected harmful factors

Solution Approach 1:

A voltage rail collapse detection circuit acts as an intermediary between the power management system and the transmitter circuit. When voltage collapse is detected, this intermediary triggers protective mechanisms (disabling the transmitter or clamping voltages) that prevent electrical overstress from reaching the thin-oxide transistors, thus resolving the contradiction between high density and stress susceptibility

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary detection of voltage rail collapse conditions before they can cause damage to the transistors. By monitoring voltage levels and predicting collapse scenarios in advance, the system can proactively disable protective mechanisms or adjust operating parameters to prevent electrical overstress before it occurs, allowing thin-oxide transistors to operate safely at high densities

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If transmitter circuits are designed to support different memory standards with different voltage ranges, then adaptability is improved, but integrity of transistors in low-voltage circuits is compromised

Engineering Contradiction:

Improvemulti-standard supportVSAvoidtransistor integrity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The transmitter circuit employs dynamic voltage adjustment and mode switching capabilities. Voltage rails can be dynamically collapsed to zero volts when not needed, and the circuit can switch between different operating modes (e.g., normal mode, low-power mode, disabled mode) depending on which memory standard is active. This dynamic behavior allows the circuit to adapt to different voltage requirements while protecting thin-oxide transistors from exposure to incompatible voltage levels

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes operating parameters (voltage levels, signaling schemes, driver circuit configurations) based on the detected memory standard. By adjusting these parameters dynamically, the transmitter can support multiple standards with different voltage ranges while ensuring that thin-oxide transistors are never exposed to voltage levels beyond their tolerance, thus maintaining both adaptability and reliability

Inventive Principle:

Principle #35Parameter changes

3Loss of energy

If voltage of a third voltage rail is collapsed to zero-volt level to save power, then energy consumption is reduced, but electrical overstress occurs in thin-oxide transistors

Engineering Contradiction:

Improvepower consumptionVSAvoidelectrical overstress

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The system applies preliminary protective actions by detecting when voltage rail collapse is about to occur or is occurring, and simultaneously disables the transmitter circuit or clamps the voltage across thin-oxide transistors to safe levels. This preliminary anti-action prevents the harmful effect (electrical overstress) from occurring even though the voltage collapse (energy-saving mechanism) is taking place

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

A protective circuit acts as an intermediary between the collapsing voltage rail and the thin-oxide transistors. This intermediary monitoring circuit detects the voltage collapse condition and triggers protective measures (such as disabling switches or activating clamp circuits) that prevent the full force of the voltage collapse from reaching the sensitive transistors, thus allowing energy-saving voltage collapse while protecting against overstress

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12211578B2DDR PHY power collapse circuit for multimode double data rate synchronous dynamic random access memory

Publication Date: 2025.01.28 QUALCOMM INC

AI summary

A transmitter circuit includes a first driver circuit configured to drive an input/output pad in an integrated circuit device, the first driver circuit including a thin-oxide transistor configured to couple the input/output pad to a first voltage rail when the transmitter circuit is operated in a first mode; a gate pullup transistor configured to couple a gate of the thin-oxide transistor to a second voltage rail when voltage of a third voltage rail is collapsed to a zero-volt level; and a switch configured to block transmission of a gating signal to the gate of the thin-oxide transistor when the voltage of the third voltage rail is collapsed to the zero-volt level.