USB Interface Module for DC-Coupled Level Shifting Across Power Domains

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Solution Overview

Problem

Existing USB communication systems face challenges in communicating electrical signals with DC components across power domains due to significant ground voltage differences, which can lead to signal loss and incorrect signaling, especially in configurations with ground loops, and conventional level-shifting methods like series capacitors or transformers block the DC component.

Innovation Solution

An integrated circuit with an interface module that includes a digital controller in one power domain and an analog front-end circuit in another, using up/down level shifters with buffers to communicate electrical signals, including DC components, without series capacitors, transformers, or opto-electric coupling, thereby isolating power domains and maintaining signal integrity across USB standards like USB 2.0.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If series capacitors are used for AC coupling to address ground-offset voltages, then ground voltage differences can be managed, but the DC component of electrical signals is blocked

Engineering Contradiction:

Improveground voltage difference managementVSAvoidDC component blocking

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent introduces level shifters as intermediary devices between the first and second power domains. These level shifters translate voltage levels and accommodate ground offset voltages without blocking the DC component, thereby maintaining signal integrity while managing ground voltage differences.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent dynamically adjusts voltage level parameters using level shifters that can adapt to varying ground offset conditions. By changing the voltage translation parameters in real-time, the system maintains DC signal passage while compensating for ground voltage differences up to 250mV.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If transformers or opto-electric coupling are used to address ground-offset voltages, then ground loops can be isolated, but the DC component of electrical signals is blocked

Engineering Contradiction:

Improveground loop isolationVSAvoidDC component blocking

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The level shifter acts as an intermediary that provides ground loop isolation through controlled impedance paths and virtual ground techniques, without requiring transformers or opto-electric couplers. This maintains DC signal continuity while protecting against ground offset effects.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If USB power delivery configurations are used to enable charging, then power can be delivered, but significant ground voltage differences occur that can exceed USB standards

Engineering Contradiction:

Improvepower deliveryVSAvoidground voltage offset

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The level shifters dynamically adjust their voltage translation parameters based on the ground offset conditions detected in the USB power delivery configuration. This allows the system to maintain reliable communication despite ground voltage differences that can reach 250mV or more in complex power delivery scenarios.

Inventive Principle:

Principle #35Parameter changes

4Use of energy by moving object

If ground loops are created in complex ground networks, then power delivery can be achieved, but ground voltage differences increase to the point where communication cannot be recovered

Engineering Contradiction:

Improvepower deliveryVSAvoidcommunication recovery

Core Design Contradiction:

Use of energy by moving objectVSLoss of information

Solution Approach 1:

The level shifters serve as protective intermediaries that isolate the communication circuitry from ground loop effects. By providing controlled impedance paths and virtual ground references, they prevent ground voltage differences from corrupting the data communication, even in complex power delivery configurations with multiple ground paths.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS11921651B2Interface module with low-latency communication of electrical signals between power domains

Publication Date: 2024.03.05 AYDEEKAY LLC

AI summary

An integrated circuit is described. This integrated circuit may include: an interface module with a first power domain and a second power domain. The first power domain may include a digital controller, and the second power domain may include a first analog front end (AFE) circuit. Moreover, the interface module may include up/down level shifters that communicate electrical signals that include a DC component from the first power domain to the second power domain. In some embodiments, the integrated circuit may provide a fully on-chip solution to handle level shifting between the AFE circuit and a digital controller in Universal Serial Bus (USB) 2.0 during communication of electrical signals in a full-speed mode and/or a high-speed mode.