Transformer-Based Transceiver Signal Isolation

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Solution Overview

Problem

Existing transceivers face challenges in full duplex communication due to internal interference between transmitter and receiver signals, particularly when using frequency division duplex (FDD), as duplexers are costly, space-consuming, and difficult to implement on-chip, and existing on-chip solutions like dummy loads result in energy loss.

Innovation Solution

A transceiver design that uses a transformer with a primary winding connected in parallel to a signal transferring element, such as an amplifier or filter, to suppress transmitter signals at the receiver input, eliminating the need for duplexers and dummy loads by maintaining unity gain or attenuation across the primary winding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a duplexer is used to enable full duplex communication, then simultaneous transmission and reception is achieved, but cost, space consumption, and implementation difficulty increase

Engineering Contradiction:

Improvefull duplex communication capabilityVSAvoidduplexer implementation complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent extracts the interference suppression function from the traditional duplexer structure and implements it separately using a transformer and dummy load, eliminating the need for a complex duplexer while maintaining full duplex capability

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The signal path is segmented into separate transmission and reception paths using a transformer, with the primary winding handling transmission signals and the secondary winding handling received signals, allowing independent optimization of each path

Inventive Principle:

Principle #1Segmentation

2Object-generated harmful factors

If a dummy load is used to balance impedance and suppress transmitter signals, then transmitter interference at receiver input is reduced, but transmission energy is lost in heat dissipation

Engineering Contradiction:

Improvetransmitter signal interference at receiverVSAvoidenergy loss in dummy load

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The patent converts the potentially harmful transmitter signal into a useful reference signal by using it to drive the primary winding of the transformer, which then generates a compensating signal at the secondary winding that cancels out the interference at the receiver input

Inventive Principle:

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

Solution Approach 2:

The transformer acts as an intermediary between the transmitter and receiver, transferring the transmitter signal to the primary winding and generating a compensated signal at the secondary winding that suppresses interference without dissipating energy as heat

Inventive Principle:

Principle #24Intermediary (Mediator)

3Device complexity

If the same antenna is used for both transmission and reception, then hardware complexity is reduced, but internal interference occurs between transmitter and receiver signals

Engineering Contradiction:

Improveantenna system complexityVSAvoidinternal interference within transceiver

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

The transformer serves as an intermediary that separates the transmission and reception signal paths electrically, allowing the same antenna to be shared while preventing direct interference between transmitter and receiver through magnetic coupling isolation

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 isolates transmitter signals from the receiver input, reducing internal interference and eliminating the need for costly duplexers, while maintaining efficient signal transmission and reception, suitable for frequency division duplex communication in various devices.

Implementation Method 1

a transformer with a primary winding connected in parallel to a signal transferring element... wherein the first winding is electrically connected in a circuit path which is connected in parallel to the first signal transferring element, and the second winding is connected to an input of the receiver

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Data Source

PatentUS9143186B2Transceiver and communication device

Publication Date: 2015.09.22 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A transceiver comprises a receiver, a transmitter, a signal transmission arrangement, a first signal transferring element, and a transformer having magnetically-connected first and second windings. The first signal transferring element is between the transmitter output and the signal transmission arrangement, which is arranged to transmit signals from the transmitter and to receive signals and provide them to the receiver. The first winding of the transformer is connected in parallel with the first signal transferring element, which has input and output impedances so that signals from the transmitter output reach the signal transmission arrangement, while signals from the signal transmission arrangement do not reach the transmitter output. As such, the first signal transferring element is arranged to transfer signals from the transmitter to the signal transmission arrangement such that the transmitter contribution to the signal in the first winding is suppressed.