Non-Linear PA Mode Switching in Wi-Fi 7 RF Front Ends

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Solution Overview

Problem

Current RF FE designs in access points are insufficient for supporting higher modulation and EIRP requirements of IEEE 11be/WiFi7, leading to cost-inefficiency and power limitations due to the need for multiple PAs, which exceed the power draw allowed by Power over Ethernet (POE).

Innovation Solution

Implementing non-linear power amplifiers (PAs) with adjustable bias voltage and backoff regions in analog front ends, allowing dynamic switching between high and low linearity modes based on link conditions and AFC modes to optimize power usage and support multi-link operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple PAs are added to support multi-link operation, then the capability to support higher modulation and EIRP is improved, but the cost and total power draw increase

Engineering Contradiction:

Improvemulti-link operation capabilityVSAvoidtotal power draw

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by stationary object

Solution Approach 1:

The patent applies dynamics by making the PA operating mode adjustable rather than fixed. The system can dynamically switch between linear and non-linear PA modes based on the specific link requirements, allowing a single PA to adaptively support different numbers of links and power levels without requiring multiple dedicated PAs.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the operating parameters of the PA by adjusting the backoff region value. By varying this parameter, the same PA can operate in different modes (linear vs non-linear) to match different transmission requirements, enabling a single PA to replace multiple PAs for different operational scenarios.

Inventive Principle:

Principle #35Parameter changes

2Adaptability or versatility

If multiple PAs are added to support multi-link operation, then the capability to support higher modulation and EIRP is improved, but the cost increases

Engineering Contradiction:

Improvemulti-link operation capabilityVSAvoidcost

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent makes a single PA unit universal by enabling it to perform multiple functions through mode switching. The same PA can serve as a linear PA for high EIRP requirements or as a non-linear PA for cost-sensitive applications, eliminating the need to purchase and manage multiple dedicated PA units for different scenarios.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The dynamic configurability of the PA allows it to adapt its behavior based on the application requirements. This dynamic nature replaces the need for static multiple PA designs, reducing manufacturing complexity and component count while maintaining the ability to support various multi-link configurations.

Inventive Principle:

Principle #15Dynamics

3Power

If linear PA is used to support higher EIRP, then the power output is improved, but the cost and power consumption increase

Engineering Contradiction:

ImproveEIRPVSAvoidpower consumption

Core Design Contradiction:

PowerVSUse of energy by stationary object

Solution Approach 1:

The patent changes the PA operating parameters by adjusting the backoff region to enable non-linear operation. This parameter change allows the PA to achieve high EIRP output without requiring the higher power consumption associated with linear PA operation, as the non-linear mode provides sufficient performance for many practical applications at lower power levels.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent accepts that non-linear PA operation may have limited applicability in specific high-performance scenarios, but uses this approach to provide cost-effective and low-power solutions for the majority of practical applications, where the trade-off between maximum EIRP and power consumption is not critical.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

4Adaptability or versatility

If non-linear PA with adjustable bias voltage is used, then the adaptability to different link conditions is improved, but the device complexity increases

Engineering Contradiction:

Improvelink condition adaptationVSAvoidcontrol mechanism

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements adaptability by adjusting the bias voltage and backoff region parameters of the PA. These parameter changes enable the system to adapt to different link conditions and operational requirements. The control mechanism involves standard voltage regulation and configuration interfaces that are commonly found in RF systems, avoiding the need for complex specialized hardware.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20250310895A1Adaptive fe linearity with non-linear pa

Publication Date: 2025.10.02 CISCO TECHNOLOGY INC

AI summary

The embodiments herein describe using non-linear PAs (rather than linear PAs) in analog FEs in network devices, such as APs. In one embodiment, a mode of operation of the non-linear PA is switched in response to conditions of a wireless link. When satisfying a performance threshold, the AP operates the non-linear PA in a High Linearity Operating mode where the PA is biased at a higher voltage and a backoff region of the PA is increased. If the performance threshold is not satisfied, the AP operates the non-linear PA in a low (or mid) Linearity Operating mode where the PA is biased at a lower voltage and the backoff region of the PA is decreased. In another embodiment, the non-linear PA can be used to support Standard Power used by Automated Frequency Coordination.