Selective RF Power Amplifier Paths Without Output Switching

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing radio-frequency power amplifiers face challenges with costly output switches and performance degradation due to large matching bandwidth, leading to mismatch, ohmic losses, and reliability issues as the number of frequency bands increases in multi-mode multi-band devices.

Innovation Solution

A power amplifier design with multiple signal paths sharing a common input, each equipped with a dedicated amplifier stage and a bias selector, allowing for selective amplification and elimination of the need for an external output switch by using dedicated matching networks and harmonic traps for improved power efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single power amplifier with output switch is used to support multiple frequency bands, then device complexity is reduced, but mismatch losses and ohmic losses increase due to large matching bandwidth requirements

Engineering Contradiction:

Improvenumber of amplifiersVSAvoidmismatch losses

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The power amplifier is segmented into multiple independent signal paths, each dedicated to a specific frequency band. Each signal path includes its own amplifier stage and matching network, allowing each path to be optimized for its specific band without compromising performance for other bands. This segmentation eliminates the need for a single wideband matching network that causes high losses.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of using a single amplifier with a switch at the output to select frequency bands, the invention inverts the approach by using multiple amplifiers with a switch at the input. The switch selects which signal path receives the input signal, and each path is independently optimized for its specific frequency band, eliminating mismatch losses associated with wideband matching.

Inventive Principle:

Principle #13The other way round (Inversion)

2Adaptability or versatility

If output switches are used to route amplified signals for different frequency bands, then band selection is achieved, but reliability decreases and cost increases

Engineering Contradiction:

Improveband selection capabilityVSAvoidsystem reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention inverts the conventional approach by placing the switch at the input rather than the output. This input-side switching protects the amplifier stages from potential damage when not in use, as the switch isolates them from the input signal. It also reduces the power handling requirements of the switch, allowing for more reliable and cost-effective switch implementation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The switch is positioned beforehand in the signal path to protect the amplifier stages. When a particular frequency band is not selected, the switch prevents the input signal from reaching the corresponding amplifier stage, thereby cushioning it against potential damage from operating outside its optimal range or from excessive power levels.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If a single power amplifier is used for multiple frequency bands, then device complexity is reduced, but power efficiency decreases due to ohmic losses

Engineering Contradiction:

Improvenumber of amplifiersVSAvoidpower efficiency

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Each signal path is designed with local quality optimization, where the matching network and amplifier stage are specifically tuned for the frequency characteristics of that particular band. This ensures maximum power efficiency and minimum ohmic losses for each frequency band, rather than using a compromise wideband design.

Inventive Principle:

Principle #3Local quality

4Adaptability or versatility

If the number of frequency bands is increased in multi-mode multi-band devices, then adaptability is improved, but mismatch losses and reliability issues increase

Engineering Contradiction:

Improvefrequency band coverageVSAvoidohmic losses

Core Design Contradiction:

Adaptability or versatilityVSLoss of energy

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The multi-path architecture provides universal support for multiple frequency bands through dedicated paths. Each path can be independently activated based on the required frequency band, allowing the system to maintain optimal performance across all supported bands without the compromises inherent in single-wideband designs.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10312864B2Power amplifier having selective signal paths

Publication Date: 2019.06.04 SKYWORKS SOLUTIONS INC

AI summary

Power amplifier having selective signal paths. In some embodiments, a power amplifier circuit can include a plurality of signal paths sharing a common amplification stage configured to partially amplify a signal. Each signal path can further include a dedicated amplification stage coupled to the common amplification stage and configured to be capable of further amplifying the partially amplified signal. The power amplifier circuit can further include a bias selector having a switch configured to provide a bias signal to a selected dedicated amplification stage among the plurality of signal paths to thereby allow the selected dedicated amplification stage to further amplify the partially amplified signal.