Dual-Voltage Chip Select Transmitters for LPDDR Switching

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Solution Overview

Problem

Existing memory interface circuits struggle with reliable transitions between different operational states, requiring changes in voltage levels, which impact switching speed and data rates in mobile devices.

Innovation Solution

A dual-transmitter circuit system is employed, with one transmitter operating at a higher voltage for power-down modes and another at a lower voltage for normal modes, ensuring seamless transitions and maintaining high data rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If voltage level is increased for power-down mode transitions, then reliability of state transitions is improved, but power consumption increases

Engineering Contradiction:

Improvereliability of state transitionsVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The transmitting circuit is divided into multiple independent transmitters, each dedicated to a specific voltage level (first transmitter for first voltage level, second transmitter for second voltage level). This segmentation allows the system to select the appropriate transmitter based on operational mode, ensuring reliable transitions at required voltage levels while avoiding unnecessary power consumption from inactive transmitters.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If voltage level is decreased for normal mode operation, then power efficiency is improved, but switching speed may be reduced

Engineering Contradiction:

Improvepower efficiencyVSAvoidswitching speed

Core Design Contradiction:

Use of energy by moving objectVSSpeed

Solution Approach 1:

The system dynamically switches between different transmitters based on operational mode requirements. During normal mode, the first transmitter operates at lower voltage for power efficiency. During power-down mode transitions, the second transmitter activates at higher voltage to ensure fast, reliable transitions. This dynamic adaptation resolves the contradiction between power efficiency and switching speed.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If dual-transmitter system is implemented for multiple voltage levels, then adaptability to different operational states is improved, but device complexity increases

Engineering Contradiction:

Improveadaptability to different operational statesVSAvoidcomplexity of transmitting circuit

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Both transmitters share common input connections to the chip select signal source and common output connections to the output node. This universal interface design allows the dual-transmitter system to support multiple voltage levels and operational modes without requiring separate dedicated circuits for each mode, thereby reducing overall complexity while maintaining adaptability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12424265B2Chip select transmitters for multiple signal levels

Publication Date: 2025.09.23 QUALCOMM INC

AI summary

A signal driving circuit includes a first transmitting circuit having an input coupled to a source of a chip select signal and an output that is configured to switch within a first voltage range having a first amplitude, a second transmitting circuit having an input coupled to the source of the chip select signal and an output that is configured to switch within a second voltage range having a second amplitude, and an output node coupled to the output of the first transmitting circuit and the output of the second transmitting circuit. The first amplitude may be lower than the second amplitude.