Interference Resistant Local Oscillator Using Segmented Chip Layout

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Solution Overview

Problem

Conventional local oscillator (LO) generation methods face challenges in generating clean high-frequency signals above 1 GHz, leading to interference and spectral compliance issues, especially when implemented in a single chip with higher power transmitters, resulting in costly and power-consuming solutions.

Innovation Solution

Operating the voltage controlled oscillator (VCO) at an integer multiple above the desired transmission frequency, using a divide-by-N frequency divider, and employing silicon isolation and noise-resistant inductors to reduce interference, along with optimized inductor geometries and power delivery systems to enhance stability and resistance to electromagnetic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a VCO is implemented on the same chip as a high-power transmitter, then device integration and cost are improved, but electromagnetic interference from the high-power section degrades the VCO signal quality

Engineering Contradiction:

Improvedevice integrationVSAvoidelectromagnetic interference

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The chip is divided into distinct functional sections with a low-power VCO section and a high-power transmitter section. Physical separation and strategic placement of these sections reduce electromagnetic coupling while maintaining single-chip integration benefits.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Neutralization circuits are introduced as intermediary elements between the high-power transmitter and the VCO. These circuits generate counter-phase signals that cancel out harmful electromagnetic emissions from the transmitter, protecting the VCO without requiring complete physical isolation.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Speed

If conventional LO generation methods are used above 1 GHz, then signal generation is achieved, but harmonics and spurs increase causing spectral compliance issues

Engineering Contradiction:

Improvesignal generation frequencyVSAvoidharmonics and spurs

Core Design Contradiction:

SpeedVSObject-generated harmful factors

Solution Approach 1:

The neutralization circuits convert the harmful high-frequency harmonics and spurs generated by the VCO into beneficial counter-signals. By generating signals at the same frequency but with opposite phase, these circuits cancel out the unwanted spectral components while maintaining the desired LO signal.

Inventive Principle:

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

Solution Approach 2:

The operating frequency of the VCO is changed to an integer multiple (N times) of the desired transmission frequency. This frequency multiplication approach, combined with neutralization, allows generation of clean high-frequency signals with reduced harmonics and improved spectral compliance.

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If the VCO is placed close to the high-power transmitter section, then chip area is reduced, but frequency pulling and signal degradation occur

Engineering Contradiction:

Improvechip areaVSAvoidVCO signal stability

Core Design Contradiction:

Area of stationary objectVSReliability

Solution Approach 1:

The chip layout is segmented into distinct low-power and high-power sections with optimized spacing and orientation. This physical segmentation allows compact integration while maintaining sufficient isolation to prevent frequency pulling and signal degradation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Neutralization circuits are positioned as intermediary elements between the VCO and high-power transmitter sections. These circuits actively compensate for electromagnetic coupling effects, enabling closer placement of components without compromising VCO signal stability.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 approach effectively reduces interference in local oscillators, allowing for more compact and cost-effective transceivers with improved spectral purity and reduced power consumption, suitable for both low and high-power transmission systems.

Implementation Method 1

a voltage controlled oscillator operates at an integer multiple (N) above the desired transmission frequency

Methodology Applied

Scientific EffectOscillation: Harmonic Oscillator

Implementation Method 2

The VCO signal may be distributed to multiple radios at the higher frequency and a divide-by-N frequency divider may be used

Methodology Applied

Scientific EffectFrequency division:

Implementation Method 3

employing silicon isolation and noise-resistant inductors to reduce interference

Methodology Applied

Scientific EffectElectromagnetic isolation:

Implementation Method 4

employing silicon isolation and noise-resistant inductors to reduce interference, along with optimized inductor geometries

Methodology Applied

Scientific EffectMagnetic energy storage: Inductor

Data Source

PatentUS8970314B2Interference resistant local oscillator

Publication Date: 2015.03.03 INTEL CORP

AI summary

With some embodiments, a VCO (voltage controlled oscillator) operates at an integer multiple (N) above a desired transmission frequency. In accordance with one embodiment, a chip is provided with a VCO to generate a signal and a frequency dividing circuit to provide a reduced frequency version of the signal to a transmit mixer. The transmit mixer is followed by a power amplifier that is on the same die as the VCO. The power amplifier is to generate an OFDM output transmission.