High-Voltage Doherty PA Without Impedance Transformation
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Solution Overview
Problem
Traditional Doherty power amplifiers for RF applications suffer from increased loss and complexity due to the need for impedance transformation networks and band selection switches, which degrade transmit efficiency and increase size and cost.
Innovation Solution
A high-voltage Doherty power amplification system that eliminates impedance transformation networks by using a boost DC/DC converter to generate a high-voltage supply signal, allowing the Doherty power amplifiers to operate at a 50 Ohm impedance without the need for impedance transformation, and eliminates band selection switches by using separate Doherty PAs for each frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If impedance transformation networks are used in traditional Doherty power amplifiers, then impedance matching is achieved, but loss increases and efficiency decreases
Solution Approach 1:
The patent removes impedance transformation networks from the output path of the Doherty power amplifier, extracting the problematic component that caused both losses and complexity. The high-voltage operation mode enables direct connection to the filter without intermediate impedance transformation stages.
Solution Approach 2:
The patent changes the operating voltage parameter to high-voltage mode, which fundamentally alters the impedance characteristics of the power amplifier. This parameter change enables the amplifier to operate at 50 Ohms directly, eliminating the need for impedance transformation networks and their associated losses.
2Adaptability or versatility
If band selection switches are used to handle multiple frequency bands, then versatility is improved, but device complexity and size increase
Solution Approach 1:
The patent divides the single power amplifier into multiple separate Doherty PAs, each dedicated to a specific frequency band. This segmentation eliminates the need for band selection switches and complex routing logic, as each amplifier handles its designated band independently and connects directly to its corresponding filter.
Solution Approach 2:
Instead of using a single amplifier with switches to select bands (centralized approach), the patent inverts the architecture by using multiple amplifiers without switches (distributed approach). Each amplifier is permanently connected to its designated filter, eliminating the switching complexity while maintaining multi-band capability.
3Area of stationary object
If impedance transformation networks are included in the output path, then impedance matching is achieved, but the overall system size increases
Solution Approach 1:
The patent extracts and removes impedance transformation networks from the output path, eliminating both the physical space they occupy and the complexity they introduce. The high-voltage operation enables direct connection from the power amplifier to the filter.
Solution Approach 2:
The patent merges the function of the power amplifier with the filter by eliminating intermediate impedance transformation networks. The simplified output path directly connects the amplifier to the filter, reducing overall system size and complexity while maintaining performance.
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 significantly reduces loss and simplifies the power amplification system, achieving higher efficiency and smaller die sizes, while maintaining competitive size and cost targets, and allows for independent optimization of each frequency band.
Implementation Method 1
The supply system can include a boost DC/DC converter configured to generate the HV supply signal based on a battery voltage Vbatt
Data Source
AI summary
Doherty power amplifier having reduced size. In some embodiments, a power amplification system can include a supply system configured to provide a high-voltage supply signal, and a Doherty power amplifier configured to receive the high-voltage supply signal and amplify a radio-frequency (RF) signal. The power amplification system can further include an output path configured to receive and route the amplified RF signal to a filter. The output path can be substantially free of an impedance transformation circuit.