Envelope Tracking Power Amplifier With Impedance-Modifying Auxiliary Path
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designing wireless communications devices that efficiently transfer power across multiple frequency bands while minimizing antenna size and reducing losses due to impedance mismatch and high Peak-to-Average Power Ratios (PAPRs) in RF power amplifiers, especially for devices with limited battery power and varying transmit power requirements.
Innovation Solution
A power amplifier apparatus comprising a main linear amplifier sub-circuit and an auxiliary linear amplifier sub-circuit, with a combining network that generates an impedance modifying signal to optimize power transfer, using a complex scaling factor to adjust impedance and maximize electrical power delivery to the antenna, and an envelope tracking system to adjust supply voltage based on the signal envelope.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If an antenna tuning unit with switched capacitor networks is used to improve power transfer, then impedance matching is improved, but power losses increase due to undesirable losses in the tuneable matching networks
Solution Approach 1:
The patent replaces the mechanical/electronic switching mechanism (switched capacitor networks) with a signal processing approach. The auxiliary amplifier sub-circuit generates an impedance modifying signal through signal manipulation rather than physical component switching, eliminating the inherent losses associated with switched capacitor networks while maintaining impedance matching capability.
Solution Approach 2:
The patent introduces an auxiliary amplifier sub-circuit as an intermediary element that generates an impedance modifying signal. This intermediary signal works in conjunction with the main amplified signal to achieve impedance matching without requiring lossy passive components, thereby reducing power losses while maintaining ease of manufacture.
2Productivity
If the auxiliary linear amplifier sub-circuit amplifies substantially more than half of each wave cycle, then power transfer efficiency is improved, but device complexity increases
Solution Approach 1:
The patent employs dynamic operation of the auxiliary amplifier sub-circuit, which amplifies substantially more than half of each wave cycle of the impedance modifying signal. This dynamic approach allows the system to adapt to varying signal conditions and optimize power transfer efficiency across different operating points, while the complexity is managed through integrated circuit design rather than discrete component assemblies.
Solution Approach 2:
The patent combines the main linear amplifier sub-circuit and auxiliary linear amplifier sub-circuit into a unified power amplifier apparatus with a shared combining network. This merging of functions allows the two sub-circuits to work synergistically, improving power transfer efficiency while managing overall device complexity through functional integration rather than separate independent systems.
3Adaptability or versatility
If multiple generations of communications systems operate side-by-side, then system versatility is improved, but power amplifier efficiency deteriorates due to wide frequency range requirements
Solution Approach 1:
The power amplifier apparatus is designed with universal functionality to operate across wide frequency ranges required for multiple generations of communications systems. The main and auxiliary amplifier sub-circuits work together to provide consistent performance across different frequency bands, maintaining power amplifier efficiency despite the versatility requirements through coordinated operation rather than separate optimized circuits for each band.
Data Source
AI summary
An amplifier apparatus (332) comprises a main linear amplifier sub-circuit (402) having a main driving signal input terminal (331) and a main amplifier output terminal (406). The apparatus also comprises an auxiliary linear amplifier sub-circuit (404) having an auxiliary driving signal input terminal (357) and an auxiliary amplifier output terminal (408). A combining network (410) is operably coupled between the main amplifier output terminal (406) and the auxiliary amplifier output terminal (408), the combining network (410) having a main-side terminal (424) and an auxiliary-side terminal (434). The main linear amplifier sub-circuit (402) is arranged to generate, when in use, a main amplified signal in response to a main driving signal applied at the main driving signal input terminal (331). The auxiliary linear amplifier sub-circuit (404) is arranged to generate, when in use, an impedance modifying signal at the auxiliary-side terminal (357) in response to an auxiliary driving signal and at substantially the same time as the main linear amplifier sub-circuit (402) generates the main amplified signal, the auxiliary linear amplifier sub-circuit (404) also being arranged to amplify substantially more than half of each wave cycle of the auxiliary driving signal.