Active Probe Powering via Driven Coax Cable

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Solution Overview

Problem

Existing measurement systems require separate conductors for powering active probes and signal transmission, leading to bulky and costly connector systems, as well as the need for interface panels to route multiple probes to a single oscilloscope channel.

Innovation Solution

Delivering power to active probes over the same coaxial cable that carries signals back to the oscilloscope, eliminating the need for multi-conductor cables and interface panels by using a head-end circuit that applies DC power and removes voltage offsets, allowing for easier switching of multiple probes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate conductors are used for powering active probes and signal transmission, then power delivery and signal transmission can be performed independently, but the connector system becomes bulky and costly

Engineering Contradiction:

Improvepower delivery reliabilityVSAvoidconnector system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines power delivery and signal transmission functions into a single coaxial cable. The power delivery network (PDN) is integrated within the coaxial cable structure, allowing both power and signal to be transmitted through the same physical medium. This eliminates the need for separate conductors and reduces connector complexity while maintaining reliable power delivery to active probes.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The coaxial cable is designed to serve multiple functions simultaneously: it acts as both a power delivery conduit and a signal transmission medium. The PDN integrated within the coaxial cable enables the same cable to handle both electrical power and high-frequency signal transmission, reducing the overall system complexity and eliminating the need for specialized multi-conductor cables.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If interface panels are used to route multiple probes to a single oscilloscope channel, then probe switching is possible, but the system becomes more complex and costly

Engineering Contradiction:

Improveprobe switching capabilityVSAvoidinterface panel complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the probe switching function from the traditional interface panel architecture and integrates it directly into the oscilloscope's channel input. By incorporating the PDN and switching capability at the channel level rather than requiring a separate interface panel, the system achieves probe switching capability with reduced complexity and cost.

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If multi-conductor cables are used to provide both power and signal, then both functions can be delivered, but the cables become expensive and bulky

Engineering Contradiction:

Improvepower and signal deliveryVSAvoidcable cost and availability

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent utilizes inexpensive, readily available coaxial cables instead of expensive, specialized multi-conductor cables. By integrating the PDN within the standard coaxial cable structure, the system achieves both power and signal delivery using a common, cost-effective cable type that is easily manufactured and widely available.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 costs and complexity by using inexpensive coaxial cables and simplifying the switching process for multiple probes, while maintaining high bandwidth and precision in signal transmission.

Implementation Method 1

a head-end circuit to couple to the active probe via a cable... applying direct-current (DC) power to the cable

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

removing a DC voltage offset resulting from the applied DC power before a signal from the probe reaches the instrument

Methodology Applied

Scientific EffectVoltage reference transformation:

Data Source

PatentUS10908183B2Active probe powered through driven coax cable

Publication Date: 2021.02.02 NATIONAL INSTRUMENTS CORP

AI summary

A novel coupling system may include a head-end circuit for coupling a probe via a cable to an instrument, delivering power to the probe over the cable while the cable carries signal(s) from the probe to the instrument. The head-end circuit may include a first terminal for coupling to the probe via a cable, and may further include a second terminal for coupling to the instrument. The head-end circuit may apply direct-current (DC) power to the cable, and may remove a DC voltage offset resulting from the applied DC power before a signal from the probe reaches the instrument. The head-end circuit may include a common node coupled to the first terminal, a current source coupling the common node to a supply voltage, and a voltage source coupling the common node to a second terminal that couples to the instrument.