Single-Wire Bus Progressive Voltage Change for Ringing Control

Solution Overview

Problem

In single-wire bus circuits, pulling the bus voltage down with sufficient drive strength to overcome combined resistance can inadvertently cause bus ringing, leading to radiated noise and incorrect logic level detection.

Innovation Solution

Implementing a progressive voltage pulldown scheme where the master circuit incrementally increases drive strength over multiple clock cycles to transition the bus voltage from a higher to a lower level, preventing sudden voltage changes that cause ringing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the master circuit uses strong drive strength to pull the bus voltage down quickly, then the voltage transition speed is improved, but bus ringing is caused

Engineering Contradiction:

Improvevoltage transition speedVSAvoidbus ringing

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The voltage transition is segmented into multiple discrete steps across different clock cycles. The master circuit applies drive strength in incremental portions rather than applying full drive strength immediately, dividing the voltage transition into manageable segments that prevent ringing while maintaining acceptable transition speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The drive strength is made dynamic and adaptive rather than static. The master circuit adjusts the drive strength level based on the current state of the bus voltage and the elapsed time since the transition began, increasing drive strength progressively as the voltage approaches the target level, thereby preventing ringing while achieving fast transition.

Inventive Principle:

Principle #15Dynamics

2Object-generated harmful factors

If the master circuit uses incremental drive strength over multiple clock cycles, then bus ringing is prevented, but the transition time increases

Engineering Contradiction:

Improvebus ringingVSAvoidtransition time

Core Design Contradiction:

Object-generated harmful factorsVSLoss of time

Solution Approach 1:

The drive strength is made dynamic and adaptive rather than static. The master circuit adjusts the drive strength level based on the current state of the bus voltage and the elapsed time since the transition began, increasing drive strength progressively as the voltage approaches the target level, thereby preventing ringing while achieving fast transition.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The drive strength parameter is changed dynamically over time. The master circuit varies the drive strength parameter across different clock cycles, starting with lower values and progressively increasing them as the voltage transition progresses, which prevents ringing while minimizing total transition time.

Inventive Principle:

Principle #35Parameter changes

3Strength

If the master circuit pulls the bus voltage down with sufficient drive strength, then the combined resistance of the bus and slave circuits is overcome, but radiated noise increases

Engineering Contradiction:

Improvedrive strengthVSAvoidradiated noise

Core Design Contradiction:

StrengthVSObject-generated harmful factors

Solution Approach 1:

The voltage transition is segmented into multiple discrete steps across different clock cycles. The master circuit applies drive strength in incremental portions rather than applying full drive strength immediately, dividing the voltage transition into manageable segments that prevent ringing while maintaining acceptable transition speed.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The master circuit uses periodic action by applying drive strength in repeated cycles across multiple clock periods. This periodic application of controlled drive strength allows the system to overcome resistance gradually while the periodic nature of the action prevents sudden changes that would generate radiated noise.

Inventive Principle:

Principle #19Periodic action

Data Source

PatentUS20250300854A1Progressive voltage change in a single-wire bus circuit

Publication Date: 2025.09.25 QORVO US INC

AI summary

A single-wire bus circuit is provided. Herein, a master circuit is configured to communicate bus telegrams with multiple slave circuits over the single-wire bus. Each of the bus telegrams starts with a start-of-sequence (SOS) sequence. The master circuit is configured to signal a start of the SOS sequence by pulling the single-wire bus from a higher voltage to a lower voltage. In order to overcome a combined resistance of the single-wire bus and the multiple slave circuits, the master circuit must pull the single-wire bus down with a strong enough drive strength that may inadvertently cause bus ringing in the single-wire bus circuit. In embodiments disclosed herein, the master circuit is configured to pull the single-wire bus down to the lower voltage progressively with incremental drive strengths. As a result, the master circuit can signal the start of the SOS sequence without causing bus ringing in the single-wire bus circuit.