Distributed Error Injection Amplifier Circuit for Low-Loss Linearization
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Solution Overview
Problem
Existing power amplifier systems face inefficiencies and interaction problems due to high losses in error injection couplers and limited precision in feedforward linearization methods, particularly when handling high error signals or wide bandwidths, which are not effectively addressed by adaptive pre-distortion or feedforward techniques.
Innovation Solution
A directional amplifier circuit with multiple sub-amplifiers distributed along the output transmission line is used to inject compensation signals, reducing backward travel and increasing forward correction capability, thereby achieving high efficiency and low insertion loss, while also providing high directivity and handling large error signal amplitudes effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transformer coupling is used for error injection, then the system is simple to implement, but high losses occur and interaction problems arise between the error amplifier and main amplifier
Solution Approach 1:
The error injection function is segmented into multiple distributed sub-amplifiers along the transmission line rather than using a single transformer coupling point. This segmentation allows the compensation signal to be injected at multiple locations, reducing the portion traveling backward and minimizing interaction problems with the main amplifier.
Solution Approach 2:
A directional amplifier circuit is introduced as an intermediary device to replace the transformer coupling. This directional amplifier provides high backwards isolation, acting as a mediator that allows error signal injection while preventing interaction between the error amplifier and main amplifier, thereby reducing losses and interaction problems.
2Reliability
If directional coupler is used for error injection, then high backwards isolation is achieved, but large losses occur when handling large error signals
Solution Approach 1:
The error injection is divided into multiple segments along the transmission line using distributed sub-amplifiers. This segmentation reduces the signal amplitude that needs to be handled at each point, thereby reducing losses while maintaining high backwards isolation through the directional amplifier architecture.
Solution Approach 2:
The error injection is moved from a single-point coupling approach to a distributed multi-point injection approach along the transmission line. This dimensional change from point-to-line injection allows the system to maintain isolation while reducing losses by spreading the correction across multiple locations.
3Manufacturing precision
If feedforward linearization is used, then distortion correction is improved, but the system complexity increases due to multiple stages and loop balancing requirements
Solution Approach 1:
The feedforward correction is segmented into multiple distributed sub-amplifiers that can be independently controlled. This segmentation simplifies the overall system by allowing each sub-amplifier to handle a portion of the correction task, reducing the complexity of loop balancing while maintaining effective distortion correction.
4Use of energy by moving object
If adaptive pre-distortion is used, then efficiency is maintained, but the technique cannot effectively counteract noise and handles certain types of distortion poorly
Solution Approach 1:
The patent implements a feedforward feedback mechanism where the output signal is sampled, compared with the input signal, and the error is amplified and injected back into the output. This feedback approach effectively counteracts noise and various types of distortion while maintaining amplifier efficiency, complementing the pre-distortion technique.
Data Source
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AI summary
An amplifier circuit (200) for compensating an output signal provided at an output (212) of a circuit (210) is disclosed. The amplifier circuit (200) comprises an output transmission line (230) connected between the output (212) of the circuit (210) and an output port (240) and an amplifier (220). The amplifier (220) comprises multiple sub-amplifiers (221, 222, 223, 224), inputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled to an input transmission line (250) for receiving an error signal; and outputs of the multiple sub-amplifiers (221, 222, 223, 224) are coupled at respective places along the output transmission line (230) to inject a compensation signal to the output port (240). The error signal is derived from a reference input signal and the output signal of the circuit (210), and is amplified in the amplifier (220) into the compensation signal.