Predistortion Parameter Generation for Power Amplifier Alignment
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Solution Overview
Problem
Implementing a predistortion circuit in devices with programmable logic is challenging due to the need to negate non-linear effects of power amplifiers, requiring accurate generation of parameters to align amplitude, delay, and frequency offset between the predistortion circuit and power amplifier outputs.
Innovation Solution
A method and circuit for generating parameters in integrated circuits that involve receiving input signals, comparing outputs of the predistortion circuit and power amplifier, adjusting amplitude and eliminating delay and frequency offset, and using an estimation circuit to generate parameters for the predistortion circuit, which includes amplitude alignment, delay alignment, and frequency offset correction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a predistortion circuit is implemented in a device with programmable logic to negate non-linear effects of a power amplifier, then distortion cancellation capability is improved, but device complexity and parameter alignment difficulty increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing predistortion parameters in lookup tables before operation. The system performs channel estimation and parameter generation in advance, storing these parameters for rapid retrieval during signal transmission, thereby avoiding complex real-time calculations and simplifying the operational complexity of the predistortion circuit.
Solution Approach 2:
The patent introduces an intermediary estimation circuit that generates predistortion parameters based on channel characteristics. This intermediary component bridges the gap between the power amplifier and the predistortion circuit, automatically adjusting parameters to align amplitude, delay, and frequency offset without requiring direct complex coordination between all components.
2Manufacturing precision
If predistortion parameters are dynamically adjusted to align amplitude, delay, and frequency offset, then spectral compliance is improved, but computational complexity and processing time increase
Solution Approach 1:
The system performs channel estimation and parameter generation in advance, storing these parameters in lookup tables for rapid retrieval. This pre-computation approach achieves precise spectral compliance without requiring complex real-time calculations, as the heavy computational work is done beforehand and stored for quick access during operation.
Solution Approach 2:
The patent uses lookup tables that store pre-computed predistortion parameters. Instead of performing complex calculations in real-time, the system copies previously calculated optimal parameters from the lookup tables based on current channel conditions, thereby achieving high spectral compliance with reduced computational complexity.
3Speed
If trigonometric representations of phase difference are converted to algebraic representations, then processing speed is improved, but approximation accuracy may be reduced
Solution Approach 1:
The patent changes the mathematical representation of phase difference from trigonometric to algebraic form. This parameter transformation simplifies the calculations required for frequency offset correction, improving processing speed. The approximation introduced by this transformation is acceptable in the context of achieving real-time predistortion correction with practical accuracy requirements.
Data Source
AI summary
A method of generating parameters for a predistortion circuit in an integrated circuit is disclosed. The method comprises receiving, at the predistortion circuit, an input signal to be amplified by a power amplifier; receiving an output of the power amplifier at an input of the integrated circuit; comparing an output of the predistortion circuit with the output of the power amplifier; conforming the output of the power amplifier with the output of the predistortion circuit; and generating parameters to be applied to the predistortion circuit based upon the conformed output of the power amplifier and the predistortion circuit. An integrated circuit having a circuit for generating parameters for a predistortion circuit of the integrated circuit is also disclosed.