Doherty Amplifier Drivers With Inverse Nonlinearity for Linearity
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Solution Overview
Problem
Doherty amplifiers used in wireless communication systems face challenges in achieving both high efficiency and linearity, particularly due to non-linear mechanisms within the amplifier, which require additional hardware and software for digital predistortion (DPD) correction, leading to decreased transmitter efficiency and complex linearity enhancement.
Innovation Solution
Incorporating non-linear driver amplifiers that are biased to offset the non-linearity of the main and peaking amplifiers, allowing for improved linearity and efficiency in Doherty amplifier configurations, potentially reducing the need for complex DPD correction methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If digital predistortion (DPD) correction techniques are utilized to improve linearity, then linearity performance is improved, but additional hardware and software are required consuming additional power and thereby lowering transmitter efficiency
Solution Approach 1:
The driver amplifier is configured to exhibit non-linearity that is the inverse of the main amplifier's non-linearity in advance, so that when the signals are combined, the non-linearities cancel each other out. This preliminary compensation eliminates the need for additional DPD correction hardware and software, thereby maintaining transmitter efficiency while achieving improved linearity performance.
2Manufacturing precision
If DPD correction techniques are utilized to improve linearity, then linearity performance is improved, but device complexity increases due to additional hardware and software requirements
Solution Approach 1:
The driver amplifier is pre-configured with inverse non-linearity characteristics that directly compensate for the main amplifier's non-linearity. This preliminary action integrates the correction function into the existing driver amplifier stage, eliminating the need for separate DPD correction hardware and software modules, thereby reducing device complexity while maintaining improved linearity performance.
3Manufacturing precision
If conventional linear driver amplifiers are used, then linearity is maintained, but efficiency deteriorates at higher power outputs
Solution Approach 1:
Instead of attempting to eliminate non-linearity in the driver amplifier, the invention deliberately configures the driver amplifier to exhibit controlled non-linearity that is the inverse of the main amplifier's non-linearity. This converts the harmful effect of non-linearity into a beneficial compensation mechanism, allowing the driver amplifier to operate efficiently at higher power outputs while the combined output maintains improved linearity performance.
Data Source
AI summary
A device includes a Doherty amplifier having a main path and a peaking path. The Doherty amplifier includes a main amplifier configured to amplify a signal received from the main path and a peaking amplifier configured to amplify a signal received from the peaking path when the signal received from the peaking path exceeds a predetermined threshold. The device includes a first driver amplifier connected to the main path of the Doherty amplifier. The first driver amplifier is configured to exhibit an amplitude and phase distortion characteristic that is an inverse of an amplitude and phase distortion characteristic of the main amplifier. The device includes a second driver amplifier connected to the peaking path of the Doherty amplifier. The second driver amplifier is configured to exhibit an amplitude and phase distortion characteristic that is an inverse of an amplitude and phase distortion characteristic of the peaking amplifier.