RF Transceiver Front-End Circuit Without RF Switches

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Solution Overview

Problem

Conventional RF transceiver front-end circuits for time-domain duplex applications face challenges in achieving sufficient transmitter output and receiver sensitivity due to the limitations of conventional RF switches, leading to increased costs and complexity in manufacturing.

Innovation Solution

The design eliminates the conventional RF switch by fabricating all components of the front-end circuit on a single die using common transistor structures, leveraging the inherent switching characteristics of power amplifiers and low noise amplifiers to achieve similar functional features with reduced control lines, and incorporates a matching network to optimize impedance matching and minimize noise figure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If conventional RF switches are used to switch between transmit and receive modes, then the transceiver can operate in time-domain duplex mode, but the circuit complexity and manufacturing cost increase

Engineering Contradiction:

Improvetime-domain duplex operationVSAvoidcircuit complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the conventional RF switch from the front-end circuit by fabricating separate transmit and receive paths on a single die. The transmit path includes a power amplifier while the receive path includes a low noise amplifier, eliminating the need for switching between them.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent combines the transmit and receive circuits on a single die using common transistor structures. Both the power amplifier and low noise amplifier share the same semiconductor substrate and fabrication process, integrating multiple functions into one device.

Inventive Principle:

Principle #5Merging (Combining)

2Adaptability or versatility

If conventional RF switches are used for mode switching, then transmit and receive paths can be separated, but manufacturing cost increases

Engineering Contradiction:

Improvetransmit-receive path separationVSAvoidmanufacturing cost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent uses common transistor structures that can serve multiple functions. The same basic transistor design is used in both the power amplifier and low noise amplifier, allowing a single fabrication process to produce components with different functions.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Power

If higher current draw is used to achieve +20 dBm power levels, then transmitter output power increases, but efficiency decreases due to increased power loss as heat

Engineering Contradiction:

Improvetransmitter output powerVSAvoidpower loss as heat

Core Design Contradiction:

PowerVSLoss of energy

Solution Approach 1:

The patent optimizes the bias conditions and impedance matching of the power amplifier to achieve high efficiency at +20 dBm output power. By carefully controlling the operating parameters of the amplifier stages, the design maximizes power conversion efficiency while delivering the required output power level.

Inventive Principle:

Principle #35Parameter changes

4Power

If higher current draw is used to achieve +20 dBm power levels, then transmitter output power increases, but battery life decreases

Engineering Contradiction:

Improvetransmitter output powerVSAvoidbattery life

Core Design Contradiction:

PowerVSDuration of action of moving object

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

5Power

If impedance is lowered for the same power level with increased current, then power delivery capability improves, but matching circuit design becomes more difficult and power losses increase

Engineering Contradiction:

Improvepower delivery capabilityVSAvoidmatching circuit design

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The patent optimizes the impedance matching networks for the specific operating conditions of the amplifier. By designing the matching circuits to work with the actual impedance levels produced by the high-current amplifier stages, the patent achieves efficient power transfer without excessive complexity or losses.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS8175541B2Radio frequency transceiver front end circuit

Publication Date: 2012.05.08 SKYWORKS SOLUTIONS INC

AI summary

A front end circuit for coupling an antenna to a radio frequency (RF) transceiver for time domain duplex systems is disclosed. The front end circuit includes an antenna port, a power amplifier, a low noise amplifier, and a matching network. The output of the power amplifier and the input of the low noise amplifier are coupled to the matching network and connected in common to the antenna. The power amplifier and the low noise amplifier are activated and deactivated in sequence corresponding to the transmit and receive modes of the transceiver, and the matching network minimizes the effect that one has on the other at the designated operating frequency.