RF Frontend Power Measurement Using Shared DPD Feedback
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Solution Overview
Problem
Current WiFi RF Frontends face challenges in achieving stringent TX output power and linearity requirements due to the absence of integrated TX Power Amplifiers (PA) and RX Low-Noise Amplifiers (LNA) in CMOS technology, leading to performance degradation and increased power consumption when using external Front-End Modules (FEMs without both TSSI and DPD couplers.
Innovation Solution
The proposed solution enables closed-loop TSSI operation and DPD in WiFi RFICs by reusing DPD feedback signals to derive power information, allowing connection to FEMs with only one coupler, reducing power consumption and design effort, and maintaining performance without the need for additional external components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If external Front-End Modules (FEMs) are used without integrated TX Power Amplifier and RX Low-Noise Amplifier in CMOS technology, then the WiFi chipset can be completed, but the stringent requirements for TX output power, linearity, and RX Noise Figure cannot be achieved
Solution Approach 1:
The patent combines the TSSI power detection function and DPD feedback function into a single shared signal path using one coupler. The coupled signal is distributed to both the power detector for TSSI and the feedback path for DPD, eliminating the need for separate couplers while maintaining both functions' performance requirements.
Solution Approach 2:
The single coupler serves multiple functions: it provides the coupled signal to the power detector for TSSI operation, supplies feedback signal for DPD calibration, and enables both functions to share the same signal source. This multi-functional design reduces component count while meeting all performance specifications.
2Reliability
If external Front-End Modules (FEMs) are used with special high-voltage technologies, then TX Power Amplifier and RX Low-Noise Amplifier can be integrated, but power consumption increases and design complexity increases
Solution Approach 1:
The system uses the same coupled signal from a single coupler to serve both TSSI power detection and DPD feedback requirements. By making the signal serve itself for multiple purposes through intelligent routing and sharing, the design eliminates redundant components and reduces overall power consumption without compromising performance.
3Measurement precision
If FEMs with integrated TSSI detector are used, then accurate TX power control can be achieved, but additional external components are required increasing device complexity
Solution Approach 1:
The patent merges the TSSI power detection path and DPD feedback path into a single integrated signal flow. The power detector and feedback circuit share the same coupler and signal source, reducing the number of external components from two separate couplers to one, while maintaining full measurement precision for both functions.
4Device complexity
If FEMs with only one coupler are used, then device complexity is reduced, but both TSSI and DPD functions cannot be supported simultaneously
Solution Approach 1:
The single coupler is designed to universally support both TSSI and DPD functions by providing the coupled signal to multiple destinations. The signal path is routed to the power detector for TSSI operation and simultaneously to the feedback path for DPD calibration, enabling one component to fulfill multiple functional roles without performance degradation.
Data Source
AI summary
Examples relate to a concept for a Radio-Frequency (RF) frontend, and for a communication device comprising such an RF frontend. A radio-frequency frontend apparatus comprises a receive branch, comprising circuitry configured to obtain a received signal and a digital pre-distortion feedback signal from an external transceiver device. The radio-frequency frontend apparatus comprises power measurement circuitry configured to generate a first signal that represents a power of the received signal based on the received signal, and to generate a second signal that represents a power of an amplified signal based on the digital pre-distortion feedback signal, the amplified signal being a signal that is amplified by a power amplifier of the external transceiver device.