Shared Local Oscillator Architecture for Multi-Band FDD Transceivers

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Solution Overview

Problem

Multi-band frequency division duplex (FDD) transceivers face challenges in reducing the number of local oscillators (LOs) used, which leads to increased power dissipation and chip area, and generates spurious issues due to the complexity of generating and distributing LO signals in highly integrated RF ICs.

Innovation Solution

A multi-band FDD transceiver system that shares a single LO signal between the receiver and transmitter paths, using quadrature signal processing to downconvert and upconvert signals across multiple frequency bands, reducing the number of LOs required and minimizing spurious issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple local oscillators are used in multi-band FDD transceivers, then frequency conversion for multiple bands is achieved, but power dissipation and chip area increase

Engineering Contradiction:

Improvemulti-band operation capabilityVSAvoidpower dissipation

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent merges multiple local oscillator functions into a single LO by using quadrature mixing techniques. The single LO is distributed to multiple mixers that perform frequency conversion for different bands, eliminating the need for separate LOs per band and thus reducing power consumption while maintaining multi-band capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The single local oscillator is designed to serve multiple functions across different frequency bands. By using quadrature signal processing, the same LO signal is reused in multiple mixers to achieve frequency conversion for both uplink and downlink across multiple bands, making the LO universal rather than band-specific.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If multiple local oscillators are used in multi-band FDD transceivers, then frequency conversion for multiple bands is achieved, but chip area increases

Engineering Contradiction:

Improvemulti-band operation capabilityVSAvoidchip area

Core Design Contradiction:

Adaptability or versatilityVSArea of stationary object

Solution Approach 1:

The patent merges multiple local oscillator circuits into a single shared LO source. This consolidation dramatically reduces the chip area that would otherwise be occupied by multiple separate LO circuits, while the quadrature mixing architecture enables the single LO to support multiple bands through efficient signal processing.

Inventive Principle:

Principle #5Merging (Combining)

3Adaptability or versatility

If multiple local oscillators are used in highly integrated RF ICs, then frequency conversion is achieved, but spurious issues increase due to generation and distribution complexity

Engineering Contradiction:

Improvefrequency conversion capabilityVSAvoidspurious signals

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The patent extracts the problematic LO generation and distribution complexity from the system by using a single LO source instead of multiple independent LOs. This eliminates the interconnections and synchronization issues between multiple LOs that generate spurious signals, while the quadrature mixing technique maintains the necessary frequency conversion functionality.

Inventive Principle:

Principle #2Taking out (Extraction)

4Use of energy by moving object

If a single local oscillator is shared between receiver and transmitter, then power dissipation and chip area are reduced, but LO signal sharing complexity increases

Engineering Contradiction:

Improvepower dissipationVSAvoidLO signal distribution complexity

Core Design Contradiction:

Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent introduces quadrature mixing as an intermediary mechanism that enables a single LO to serve both receiver and transmitter functions. The quadrature mixers act as intermediaries that process the shared LO signal to perform frequency conversion for both uplink and downlink, managing the complexity of LO sharing while maintaining system functionality.

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 reduces the number of LOs, lowers power dissipation, and minimizes spurious issues, enabling more efficient and compact multi-band FDD transceivers that can support various wireless communication standards and frequency bands.

Implementation Method 1

a LO, configured to provide a LO signal to be shared between a receiver and a transmitter of the transceiver

Methodology Applied

Scientific EffectMixing:

Data Source

PatentUS12199927B2Single local oscillator in a multi-band frequency division duplex transceiver

Publication Date: 2025.01.14 ANALOG DEVICES INT UNLTD CO

AI summary

Embodiments of the present disclosure relate to multi-band FDD transceivers. An example transceiver includes a LO, configured to generate a LO signal to be shared between a receiver and a transmitter of the transceiver. Both the receiver and the transmitter use quadrature signal processing and are configured to multi-band operation. Sharing a single LO to perform frequency conversion of different frequency bands of received and transmitted signals advantageously allows reducing the number of LOs used in a multi-band FDD transceiver.