Multi-Band RF Power Amplifier Without Impedance Transformation
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Solution Overview
Problem
Current radio-frequency (RF) power amplifiers face inefficiencies due to the need for impedance transformation networks and band selection switches, which increase loss and complexity, especially in multi-band operations.
Innovation Solution
The implementation of a power amplification system that operates with high-voltage supplies and eliminates impedance transformation circuits and band selection switches, using heterojunction bipolar transistors (HBTs) like gallium arsenide (GaAs) devices, where each power amplifier drives a characteristic load impedance of a downstream component, such as a filter, without impedance transformation, allowing for reduced current drain and smaller PA dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If impedance transformation networks and band selection switches are used in traditional RF power amplifiers, then multi-band operation capability is achieved, but system loss increases and efficiency decreases
Solution Approach 1:
The patent divides the multi-band power amplifier into multiple independent single-band power amplifier modules, each optimized for a specific frequency band. This segmentation eliminates the need for band selection switches and impedance transformation networks, as each module directly drives its corresponding filter with matched impedance, thereby reducing system loss while maintaining multi-band operation capability.
Solution Approach 2:
Each power amplifier module is designed with universal characteristics to drive various filter types (bandpass, lowpass, highpass) directly without requiring impedance transformation. The modules can be selectively activated for different frequency bands, providing multi-band functionality through a simplified architecture that reduces energy loss.
2Reliability
If impedance transformation circuits are included in the output path of power amplifiers, then impedance matching is achieved, but device complexity and size increase
Solution Approach 1:
The patent extracts and eliminates the impedance transformation circuits from the power amplifier output path. Instead, each power amplifier module is designed with built-in impedance characteristics that directly match the characteristic impedance of the connected filters (typically 50 Ohms). This extraction simplifies the circuit architecture while maintaining reliable impedance matching.
3Adaptability or versatility
If band selection switches are used to route signals between multiple power amplifiers and filters, then frequency band switching is enabled, but loss and complexity increase
Solution Approach 1:
The patent segments the multi-band system into independent single-band power amplifier modules, each dedicated to a specific frequency band and directly connected to its corresponding filter. This segmentation eliminates the need for band selection switches, as there is no signal routing required between bands. Each module operates autonomously with matched impedance, reducing both complexity and loss while enabling frequency band switching through selective activation of appropriate modules.
Data Source
AI summary
In some embodiments, radio-frequency amplifiers can include a plurality of narrow band power amplifiers implemented. Each narrow band power amplifier can be configured to operate with a high voltage in an average power tracking mode and be capable of being coupled to an output filter associated with a respective individual frequency band. Each narrow band power amplifier can be sized smaller than a wide band power amplifier configured to operate with more than one of the frequency bands associated with the plurality of narrow band power amplifiers.