Front-end Receiver Mixer Multiplexing for Channel Isolation

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Solution Overview

Problem

Front-end receivers in wireless communication systems face challenges in achieving a balance between size efficiency, channel isolation, low noise figure, and linearity, particularly when selecting reception paths before or after down-conversion, which affects channel isolation and parasitic effects.

Innovation Solution

The implementation of a front-end receiver that performs down-conversion and multiplexing at the mixer level, allowing multiple reception channels to share a baseband circuit, thereby improving size efficiency and achieving balanced metrics of channel isolation, noise figure, and linearity by multiplexing down-converted signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the selection process is performed after the down-conversion process, then each reception path can be dedicated to a particular communication channel, but the front-end receiver incurs a size penalty because each reception path is paired with a baseband circuit

Engineering Contradiction:

Improvechannel dedicationVSAvoidreceiver size

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple reception paths by having them share common baseband circuits after down-conversion. Multiple RF signals are down-converted using separate mixers but then routed through a multiplexer to share common baseband processing circuits, reducing the total area required for baseband circuitry while maintaining channel dedication through selective routing

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The baseband circuits are designed to be universal and multi-functional, capable of processing multiple different RF channels through the multiplexer. Instead of having dedicated baseband circuits for each channel, a single set of baseband circuits can handle multiple channels sequentially, improving area efficiency while maintaining adaptability

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If the reception paths are placed closer to one another, then routing parasitic effects are reduced, but channel isolation deteriorates

Engineering Contradiction:

Improverouting parasitic effectsVSAvoidchannel isolation

Core Design Contradiction:

Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The patent resolves the spatial conflict by transitioning from simultaneous spatial separation to temporal separation. Instead of physically separating reception paths in space (which improves isolation but increases parasitics), the system uses time-division multiplexing where paths are separated in time domains, allowing closer physical placement while maintaining isolation through selective activation

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The system employs periodic switching of reception paths through a multiplexer that selectively connects different RF paths to the common baseband circuits at different time intervals. This periodic action ensures that only one path is active at a time, maintaining channel isolation while allowing physical proximity of all paths

Inventive Principle:

Principle #19Periodic action

3Object-generated harmful factors

If the reception paths are spaced farther apart, then channel isolation can be improved, but parasitic effects in routing increase, which leads to the degradation of noise figure and linearity

Engineering Contradiction:

Improvechannel isolationVSAvoidnoise figure and linearity

Core Design Contradiction:

Object-generated harmful factorsVSObject-affected harmful factors

Solution Approach 1:

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The multiplexer acts as an intermediary element that enables close spacing of reception paths while maintaining channel isolation. This intermediary component selectively routes signals from different paths to the common baseband circuits, decoupling the physical proximity from electrical isolation requirements

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 enables efficient use of resources, tolerates higher parasitic effects, and improves channel isolation without compromising noise figures or linearity, resulting in a balanced performance across size efficiency, channel isolation, and signal quality.

Implementation Method 1

The first mixer has a first output lead that is configured to deliver a first down-converted signal by reducing the first carrier frequency of the first RF signal

Methodology Applied

Scientific EffectFrequency mixing:

Data Source

PatentUS10931488B2Front-end transceivers with multiple reception channels

Publication Date: 2021.02.23 TEXAS INSTRUMENTS INC

AI summary

A front-end receiver includes a first mixer of a first channel, a second mixer of a second channel, and a switching circuit that is configured to select the first mixer or the second mixer during a particular time period. Upon being selected, one of the first mixer or the second mixer is configured to deliver a down-converted signal that down-converts a respective RF signal of either the first or second reception channel. As the tasks of down-conversion and multiplexing are combined at the mixer level, the first and second reception channels may share a baseband circuit while being able to provide a well-balanced metrics of channel isolation, low noise figure, and linearity.