Pre-Distortion and Feedback Circuits for Wideband Linearity
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Solution Overview
Problem
Circuits in electronics devices often exhibit nonlinearity, leading to distortion in output signals that degrade performance, and existing methods to mitigate this, such as pre-distortion and feedback, face limitations in bandwidth and robustness.
Innovation Solution
Combining pre-distortion and feedback techniques to create a system where pre-distortion attenuates distortion components and feedback corrects for nonlinearity, using adaptive models and filters to ensure wide bandwidth and stability, effectively canceling distortion within the feedback loop's bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If pre-distortion is used to attenuate distortion components, then bandwidth is improved, but robustness deteriorates
Solution Approach 1:
The patent combines pre-distortion and feedback techniques into a unified system where the pre-distortion circuit processes the input signal and the feedback circuit processes the output signal, with both correction signals summed together. This merging allows the system to achieve both wide bandwidth (from pre-distortion) and robustness (from feedback) simultaneously, resolving the technical contradiction between these two parameters.
2Reliability
If feedback is used to correct nonlinearity, then robustness is improved, but bandwidth deteriorates
Solution Approach 1:
By merging pre-distortion and feedback circuits, the system leverages the robustness of feedback while compensating for its narrow bandwidth limitation through the wideband pre-distortion component. The combined correction signal applies both feedback-based robustness and pre-distortion-based bandwidth expansion simultaneously.
3Object-generated harmful factors
If pre-distortion and feedback are combined, then distortion reduction is improved, but device complexity increases
Solution Approach 1:
The patent segments the distortion correction function into two independent circuits: a pre-distortion circuit that processes the input signal and a feedback circuit that processes the output signal. Each circuit can be independently designed and optimized, making the overall complex system more manageable and implementable despite the increased device complexity.
Data Source
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AI summary
Techniques for mitigating nonlinearity of circuits with both pre-distortion and feedback are described. An apparatus may include at least one circuit (e.g., an upconverter, a power amplifier, etc.), a pre-distortion circuit, and a feedback circuit. The circuit(s) may generate an output signal having distortion components due to their nonlinearity. The pre-distortion circuit may receive an input signal and generate a pre-distorted signal based on at least one coefficient determined by the nonlinearity of the circuit(s). The pre-distortion circuit may adaptively determine the coefficient(s) based on the input signal and an error signal. The feedback circuit may generate the error signal based on the input signal and the output signal and may filter the error signal to obtain a filtered error signal. The circuit(s) may process the pre-distorted signal and the filtered error signal to generate the output signal, which may have attenuated distortion components due to pre-distortion and feedback.