Chassis Reference Clock Isolation for Phase Noise Reduction

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Solution Overview

Problem

Modular electronic instrumentation platforms like PXIe face limitations in providing a high-quality reference clock, as the native chassis clock may not be sufficient for high-performance RF applications, and existing solutions require a slot in the chassis, limiting flexibility and performance.

Innovation Solution

A modular electronic instrumentation platform chassis with a dedicated, slot-free reference clock unit that includes vibration dampening mounts, separate power supply circuitry, and shielding to isolate power supply from reference clock circuitry, providing low phase-noise reference clocks through multiple PCB layers and cable connectors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a reference clock module is used to provide a high-quality reference clock, then the phase noise performance is improved, but the chassis slot resources are consumed

Engineering Contradiction:

Improvephase noise performanceVSAvoidslot resource flexibility

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The reference clock functionality is merged into the chassis structure itself through the backplane, eliminating the need for a separate reference clock module. The backplane integrates the reference clock generation and distribution capabilities directly into the chassis, allowing multiple instrument modules to share the same high-quality reference clock signal without consuming additional slot resources.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If the native PXIe chassis reference clock is used, then the slot resources are saved, but the clock quality is insufficient for high-performance RF applications

Engineering Contradiction:

Improveslot resource availabilityVSAvoidreference clock quality

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The reference clock quality parameter is enhanced by implementing dedicated reference clock circuitry and vibration dampening mounts in the chassis backplane. These structural modifications enable the chassis to generate and distribute a high-quality reference clock signal with low phase noise, meeting the requirements for high-performance RF applications while maintaining slot resource availability.

Inventive Principle:

Principle #35Parameter changes

3Measurement precision

If a separate reference clock module is installed, then the reference clock quality is improved, but the device complexity increases

Engineering Contradiction:

Improvereference clock qualityVSAvoidmodule configuration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

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 allows for a high-performance reference clock that is not limited by chassis form factor, frees up slot resources, and provides improved noise immunity and phase noise performance by isolating the clock from vibrations and electrical noise.

Implementation Method 1

The reference clock unit includes vibration dampening mounts that mount the reference clock unit to the frame

Methodology Applied

Scientific EffectVibration dampening: Damping

Implementation Method 2

a shield to isolate the power supply circuitry from the reference clock circuitry

Methodology Applied

Scientific EffectElectromagnetic shielding: Faraday Cage

Data Source

PatentUS9723727B2Modular electronic instrumentation chassis with integrated high performance reference clock and associated methods

Publication Date: 2017.08.01 KEYSIGHT TECHNOLOGIES INC

AI summary

The modular electronic instrumentation platform chassis is for use with a plurality of instrumentation modules and includes a frame defining a module area and a non-module area. The module area includes a plurality of slots open to a front of the frame and configured to receive instrumentation modules therein. A front panel may be carried by the front of the frame adjacent the plurality of slots. A chassis power unit is configured to provide power to the plurality of instrumentation modules received in the slots. A reference clock unit carried by the frame in the non-module area and is configured to provide a low phase-noise reference clock for the plurality of instrumentation modules received in the slots. The reference clock unit includes vibration dampening mounts that mount the reference clock unit to the frame, power supply circuitry, reference clock circuitry, a shield to isolate the power supply circuitry from the reference clock circuitry, and a plurality of reference clock outputs mounted in the front panel and coupled to the reference clock circuitry.