Subharmonic Local Oscillator Sharing in Direct-Conversion Radios

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Solution Overview

Problem

Direct conversion receivers face increased costs and weight due to the need for shielding or DC offsetting to prevent local oscillator leakage, limiting their application in various scenarios.

Innovation Solution

A system and method utilizing a subharmonic local oscillator for both direct conversion receivers and transmitters, minimizing leakage effects by sharing a single local oscillator for both functions and eliminating the need for shielding or DC offsetting.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If shielding or DC offsetting is used to prevent local oscillator leakage, then the direct conversion receiver can operate, but the weight and cost increase significantly

Engineering Contradiction:

Improvedirect conversion receiver operationVSAvoidreceiver weight

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent extracts and removes the shielding components and DC offsetting circuitry from the direct conversion receiver system. By eliminating these additional components that were previously necessary to handle local oscillator leakage, the system achieves the same operational reliability without the associated weight penalty.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent converts the harmful local oscillator leakage signal into a beneficial effect by using it to generate a pilot tone that aids in carrier recovery and synchronization. Instead of treating the leakage as unwanted interference requiring suppression, the system repurposes it as a useful signal component.

Inventive Principle:

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

2Reliability

If shielding or DC offsetting is used to prevent local oscillator leakage, then the direct conversion receiver can operate, but the cost increases significantly

Engineering Contradiction:

Improvedirect conversion receiver operationVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent removes the expensive shielding materials and DC offsetting circuitry from the system. This extraction eliminates the need to manufacture and assemble these additional components, thereby reducing overall manufacturing costs while maintaining operational reliability through the alternative leakage utilization approach.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

By converting the harmful leakage into a useful pilot tone, the system eliminates the need for costly shielding and offsetting circuitry, directly reducing manufacturing expenses while maintaining or even improving receiver performance.

Inventive Principle:

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

3Device complexity

If a single local oscillator is shared between receiver and transmitter, then component count is reduced, but leakage interference may increase

Engineering Contradiction:

Improvecomponent countVSAvoidleakage interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent merges the local oscillator function into a single shared component that serves both the receiver and transmitter. This consolidation reduces the total component count and simplifies the system architecture. The harmful leakage that would normally result from this merging is converted into a beneficial pilot tone for the receiver.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent converts the harmful leakage interference that would normally result from sharing a single local oscillator into a beneficial pilot tone signal. This approach allows the system to achieve component reduction without suffering from increased interference, as the leakage is repurposed as a useful signal for carrier recovery.

Inventive Principle:

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

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 reduces component count, minimizes unwanted signal interference, and allows for lightweight, cost-effective direct conversion systems that can operate efficiently in a wider range of applications.

Implementation Method 1

A local oscillator is connected to the direct conversion receiver, and generates a signal having a frequency equal to a subharmonic of the carrier frequency signal

Methodology Applied

Scientific EffectSubharmonic frequency generation:

Data Source

PatentUS8693959B1System and apparatus for a direct conversion receiver and transmitter

Publication Date: 2014.04.08 INTEL CORP

AI summary

A system for transmitting and receiving data is provided. The system includes a direct-conversion receiver that receives a signal modulated on a carrier frequency signal. The direct-conversion receiver includes one or more subharmonic local oscillator mixers. A local oscillator is connected to the direct conversion receiver, and generates a signal having a frequency equal to a subharmonic of the carrier frequency signal. A transmitter is connected to the local oscillator, which uses the local oscillator signal to transmit outgoing data.