PoDL Powered Device Gyrator Rectifier Eliminates DC-Coupling Inductors

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Solution Overview

Problem

Existing Power over Data Lines (PoDL) systems require expensive inductors for DC-coupling, which increase costs, especially in multi-drop systems where multiple Powered Devices (PDs) are connected to the same wire pair.

Innovation Solution

A Powered Device (PD) with a gyrator-based full-bridge rectifier that uses transistors and capacitors to emulate DC-coupling inductors, allowing for DC voltage polarity correction without the need for inductors, effectively blocking AC signals and providing the proper polarity DC voltage to the PD load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If inductors are used for DC-coupling in PoDL systems, then DC voltage can be transmitted to power PD loads, but the cost increases significantly

Engineering Contradiction:

ImproveDC voltage transmission capabilityVSAvoidsystem cost

Core Design Contradiction:

PowerVSEase of manufacture

Solution Approach 1:

The patent extracts the inductor component from the DC-coupling circuit and replaces it with an active rectifier bridge consisting of four switches and four capacitors. This removal of the expensive inductor while maintaining the DC-coupling function directly addresses the cost issue in PoDL systems.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the circuit topology from a passive inductor-based DC-coupling to an active switch-based rectifier bridge. By changing the operational parameters and control logic of the switches, the system achieves the same DC power transmission function without requiring magnetic components, thereby reducing cost.

Inventive Principle:

Principle #35Parameter changes

2Power

If inductors are used for DC-coupling, then DC voltage can be provided to PD loads, but device complexity increases

Engineering Contradiction:

ImproveDC voltage deliveryVSAvoidcircuit complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent replaces the passive magnetic field-based inductor with an electronically controlled active rectifier bridge using switches and capacitors. This substitution of mechanical/magnetic components with electronic control elements maintains power delivery capability while offering more flexible and integrated circuit implementation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If DC-coupling inductors are used in multi-drop systems, then multiple PDs can be powered, but the overall cost increases significantly

Engineering Contradiction:

Improvemulti-drop system supportVSAvoidoverall system cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The active rectifier bridge design provides universal DC-coupling functionality that can serve multiple PDs on the same wire pair. The circuit topology allows any combination of PDs to be powered simultaneously without requiring additional inductors for each device, making the solution scalable for multi-drop configurations.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 solution reduces the cost of DC-coupling by eliminating the need for inductors, maintaining high impedance to differential data signals, and supporting multiple PDs on the same wire pair, thereby enhancing the efficiency and cost-effectiveness of PoDL systems.

Implementation Method 1

A PD for a PoDL system is disclosed where the PD contains a gyrator that provides DC voltage polarity correction, DC-couples the DC voltage to the PD load, presents a high impedance to the differential data, and does not require an inductor for DC-coupling.

Methodology Applied

Scientific EffectGyrator effect:

Implementation Method 2

presents a high impedance to the differential data

Methodology Applied

Scientific EffectElectrical impedance: Electrical Resistance

Data Source

PatentUS11394315B2PoDL powered device with active rectifier bridge to obviate the need for DC-coupling inductors

Publication Date: 2022.07.19 ANALOG DEVICES INT UNLTD CO

AI summary

A Power over Data Lines (PoDL) system provides a DC voltage and differential data signals on the same wire pair. A Powered Device (PD) load is coupled to the wire pair, via a gyrator, for being powered by the DC voltage. The gyrator emulates the DC-coupling properties of inductors using active components. The gyrator includes transistors that are controlled to act as a full-bridge rectifier for ensuring a correct polarity DC voltage is applied to the PD load. Since the transistors operate in saturation and are coupled to be insensitive to differential data signals on the wire pair, the current supplied to the PD load is substantially unaffected by the differential data signals. Negative feedback circuits in the gyrator reduce fluctuations in current through the gyrator due to differential data signals on the wire pair. No inductors are required in the gyrator. A PHY is AC-coupled to the wire pair via capacitors.