Phase Noise Measurement Circuit Using Passive Delay Line

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Solution Overview

Problem

Existing phase noise measurement and cancellation systems are limited by noise floor, operational bandwidth, and vulnerability to environment noises such as cross-talk and coupling noise, which restricts their integration into larger systems.

Innovation Solution

A phase noise measurement circuit comprising a delay circuit, phase detector, and conversion circuitry that uses a voltage-controlled delay line and surface acoustic wave filter to measure and filter phase noise, along with a voltage-controlled phase shifter to suppress noise, while incorporating a DC offset cancellation circuit to mitigate noise sensitivity and coupling effects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a high-Q FBAR filter is used as delay line to extract phase noise, then noise sensitivity is improved (−162 dBc/Hz at 1 MHz offset), but operational bandwidth is limited to a very small range

Engineering Contradiction:

Improvenoise sensitivityVSAvoidoperational bandwidth

Core Design Contradiction:

Measurement precisionVSAdaptability or versatility

Solution Approach 1:

The patent changes the key parameter of the delay line from high-Q FBAR filter to passive delay line with controlled impedance transmission line, transforming the approach from resonance-based to transmission-based delay mechanism, thereby achieving wide bandwidth while maintaining low noise

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical resonance-based FBAR filter system with an electrical transmission line-based delay line, substituting the physical resonance mechanism with an electrical signal propagation mechanism that offers broader operational flexibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If an active delay line chain is used to extract phase noise, then operational bandwidth is improved, but noise contribution from the active delay line itself increases

Engineering Contradiction:

Improveoperational bandwidthVSAvoidnoise floor

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent uses a passive delay line that does not require active components, effectively replacing the 'expensive' active delay line with a simpler, lower-noise passive structure that achieves the same functional goal without the noise penalty

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent extracts and removes the active components from the delay line structure, keeping only the essential passive delay function, thereby eliminating the noise contribution from active devices while preserving the bandwidth advantage

Inventive Principle:

Principle #2Taking out (Extraction)

3Adaptability or versatility

If existing PNM circuits are integrated into larger systems, then system functionality is improved, but vulnerability to environment noises such as cross-talk and coupling noise increases

Engineering Contradiction:

Improveintegration capabilityVSAvoidenvironmental noise sensitivity

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potential harm of environmental noises by implementing differential signaling and balanced circuit topologies that reject common-mode interference, transforming the noisy environment into a condition that does not degrade performance

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The patent applies preliminary anti-action by incorporating shielding, grounding, and differential signaling structures that preemptively counteract environmental noises before they can affect the measurement, preventing cross-talk and coupling noise from degrading the signal

Inventive Principle:

Principle #9Preliminary anti-action

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

The solution achieves improved phase noise sensitivity and immunity to amplitude and environment noise, enabling wider bandwidth and better integration capabilities, with phase noise sensitivity of −110.35/−138.60 dBc/Hz, surpassing existing approaches by more than 10 dB.

Implementation Method 1

Some embodiments can comprise (1) an input of the delay circuit can receive the input signal, and an output of the delay circuit can output a delayed version of the first input signal

Methodology Applied

Scientific EffectSurface acoustic wave: Surface Acoustic Wave

Implementation Method 2

a phase detector (PD), and conversion circuitry to convert the output of the PD into a voltage signal that corresponds to a phase noise level in an input signal

Methodology Applied

Scientific EffectPhase detection:

Implementation Method 3

along with a voltage-controlled phase shifter to suppress noise

Methodology Applied

Scientific EffectVoltage-controlled phase shifting:

Data Source

PatentUS10075145B2Phase noise measurement and filtering circuit

Publication Date: 2018.09.11 RGT UNIV OF CALIFORNIA

AI summary

Methods and apparatuses for measuring a phase noise level in an input signal are disclosed. An input signal can be delayed to generate a delayed version of the input signal. Next, a phase difference can be detected between the input signal and the delayed version of the input signal. A phase noise level in the input signal can then be determined based on the detected phase difference. The measured phase noise level can then be used to suppress phase noise in the input signal.