Multi-Band RF Power Amplifier Without Matching Networks or Switches
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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 by configuring power amplifiers to drive characteristic load impedances of filters directly, using heterojunction bipolar transistors like gallium arsenide devices, and employing a boost DC/DC converter to generate high-voltage supplies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If impedance transformation networks and band selection switches are used in RF power amplifiers, then multi-band operation capability is achieved, but loss increases by at least 0.5 dB and device complexity increases
Solution Approach 1:
The patent divides the RF power amplifier system into multiple independent single-band PA modules, each optimized for a specific frequency band. Each module includes its own filter and operates independently, eliminating the need for band selection switches and impedance transformation networks. This segmentation allows direct coupling between PAs and filters, reducing loss while maintaining multi-band operation capability.
Solution Approach 2:
The patent employs dynamic band selection through independent control of multiple PA modules rather than static switching. Each PA module can be independently activated or deactivated based on the required frequency band, eliminating the need for mechanical or electronic switches that introduce loss. The system dynamically adapts to different bands by controlling which PA modules are active.
2Reliability
If impedance transformation networks are used to match PA output to filter input, then impedance matching is achieved, but device complexity and loss increase
Solution Approach 1:
The patent changes the operating parameters of the power amplifiers by operating them in class AB or class C mode with specific load impedances that directly match the filter input impedance. By carefully selecting and controlling the PA output impedance parameters, the need for external impedance transformation networks is eliminated. The PAs are designed to naturally present the correct impedance to the filters at their operating frequencies.
3Adaptability or versatility
If band selection switches are used to route signals between multiple PAs and filters, then multi-band operation is enabled, but loss and device complexity increase
Solution Approach 1:
The system is segmented into independent PA-filter pairs for each frequency band, eliminating the need for centralised band selection switches. Each PA module is directly connected to its corresponding filter, creating independent signal paths. This segmentation removes the switching complexity while maintaining the ability to operate across multiple bands by selectively activating appropriate PA modules.
4Reliability
If traditional RF power amplifiers with impedance transformation networks are used, then impedance matching is achieved, but PA dimensions increase
Solution Approach 1:
The patent extracts and removes the impedance transformation networks from the traditional RF PA architecture. By eliminating these external matching networks, the overall system size is reduced. The PAs are designed to directly drive the filters without intermediate impedance transformation components, thereby reducing the total volume occupied by the amplifier system while maintaining proper impedance matching through parameter optimization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces loss by at least 0.5 dB and allows for smaller PA dimensions, improving efficiency and reducing complexity, resulting in a lower loss and higher efficiency compared to envelope tracking systems while maintaining competitive size and cost.
Implementation Method 1
The PA can include a heterojunction bipolar transistor (HBT). The HBT can be, for example, a gallium arsenide (GaAs) device.
Implementation Method 2
The supply system can include a boost DC/DC converter configured to generate the HV supply based on a battery voltage Vbatt.
Data Source
AI summary
Circuits and devices related to radio-frequency amplifiers. In some embodiments, a radio-frequency amplifier can include a plurality of narrow band power amplifiers. 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.