Frequency-Based Predistortion Linearizer for Saturated Amplifiers
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Solution Overview
Problem
Operating amplifiers, such as power amplifiers, near saturation to improve efficiency can generate non-linearities that violate linearity specifications, making it challenging to conserve power and extend mobile operation without compromising signal quality.
Innovation Solution
A predistortion linearizer circuit that performs frequency-based predistortion signal generation, compensating for non-linearities by generating a pre-distorted signal with non-linear components that attenuate amplifier-induced non-linearities, thereby ensuring linearity specifications are met.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the amplifier operates near saturation to improve efficiency, then power consumption is reduced and battery life is extended, but non-linearities are generated that violate linearity specifications
Solution Approach 1:
The predistortion linearizer circuit applies preliminary distortion to the input signal before it reaches the amplifier. This pre-distortion is specifically designed to counteract the non-linearities that the amplifier will introduce when operating near saturation, thereby canceling out the distortion effects and maintaining linearity specifications while enabling efficient amplifier operation
Solution Approach 2:
The system generates a compensation signal with opposite polarity to the expected non-linear distortion. This anti-action signal is combined with the input signal before amplification, creating a pre-distorted signal that anticipates and neutralizes the amplifier's non-linear behavior, allowing the amplifier to operate efficiently without violating linearity requirements
2Manufacturing precision
If the amplifier operates in linear mode to maintain signal quality, then linearity specifications are met, but power consumption increases and mobile operation is limited
Solution Approach 1:
By applying predistortion before amplification, the system prepares the signal in advance to compensate for amplifier non-linearities. This allows the amplifier to operate in a more efficient region (near saturation) while the pre-applied distortion correction ensures that the final output meets linearity specifications, thereby reducing power consumption without sacrificing signal quality
3Manufacturing precision
If frequency-based predistortion is applied to attenuate non-linearities in specific frequency subsets, then linearity specifications are met, but device complexity increases
Solution Approach 1:
The frequency spectrum is divided into multiple subsets, and the predistortion linearizer circuit applies different attenuation levels to non-linearities in each frequency subset. This segmentation allows targeted correction of non-linearities where they most impact performance while using less computational resources than applying uniform correction across the entire spectrum, thereby managing device complexity
Data Source
AI summary
An apparatus is disclosed for frequency-based predistortion signal generation. In an example aspect, the apparatus includes a predistortion linearizer circuit configured to be coupled to an input of an amplifier. The amplifier has non-linearities associated with multiple frequencies. The multiple frequencies include a first subset of frequencies and a second subset of frequencies. The predistortion linearizer circuit is also configured to accept an input signal. The predistortion linearizer circuit is additionally configured to generate, based on the input signal, a compensation signal to attenuate the non-linearities existing within the first subset of frequencies more than the non-linearities existing within the second subset of frequencies. The predistortion linearizer circuit is further configured to generate a pre-distorted signal based on the input signal and the compensation signal.