Dual Pre-Distortion Transmitter for Power Amplifier Linearity
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Solution Overview
Problem
In wireless communication systems, particularly in OFDM and LTE-A, power amplifiers with high power and memory effects cause nonlinear distortion, which complicates the compensation of non-linearity, especially with carrier aggregation techniques, leading to data correctness issues.
Innovation Solution
A transmitter design incorporating two pre-distortion circuits and a pre-distortion parameters generating circuit, which use specific pre-distortion parameters to perform non-linear adjusting and zero-phase filtering on input signals to generate pre-distorted signals, and actively generate parameters to correct for power amplifier non-linearity, enhancing signal linearity and reducing distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single pre-distortion circuit is used to compensate power amplifier non-linearity, then the implementation is simple, but the compensation accuracy is insufficient when memory effects and carrier aggregation are present
Solution Approach 1:
The single pre-distortion circuit is divided into two separate pre-distortion circuits. The first pre-distortion circuit processes the first input signal using first pre-distortion parameters, while the second pre-distortion circuit processes the second input signal using second pre-distortion parameters. This segmentation allows each circuit to be optimized for specific signal characteristics and memory effects, thereby improving overall compensation accuracy while maintaining implementation feasibility
Solution Approach 2:
The invention introduces a new dimension of compensation by adding a second pre-distortion circuit that operates in parallel with the first. This dimensional expansion enables simultaneous handling of multiple input signals with different characteristics, addressing the limitations of single-circuit approaches when dealing with carrier aggregation and memory effects
2Power
If high power is used in the power amplifier to meet communication requirements, then the transmission power is sufficient, but nonlinear distortion increases affecting data correctness
Solution Approach 1:
The pre-distortion circuits apply corrective transformations to the input signals before they reach the power amplifier. By pre-distorting the signals in advance using calculated parameters that account for the amplifier's nonlinear characteristics, the system compensates for expected distortion, allowing high power operation while maintaining data correctness
Solution Approach 2:
The system uses feedback mechanisms where the pre-distortion parameters are generated based on the relationship between input signals and output signals. This feedback loop enables continuous optimization of the pre-distortion parameters to accurately counteract the power amplifier's nonlinear distortion, ensuring reliable data transmission at high power levels
Data Source
AI summary
A transmitter includes a first pre-distortion circuit, a second pre-distortion circuit, a transmitting circuit and a pre-distortion parameters generating circuit. The first pre-distortion circuit uses a plurality of first pre-distortion parameters to perform a pre-distortion operation upon a first input signal to generate a pre-distorted first input signal. The second pre-distortion circuit uses a plurality of second pre-distortion parameters to perform a pre-distortion operation upon a second input signal to generate a pre-distorted second input signal. The transmitting circuit is arranged to process the pre-distorted first input signal and the pre-distorted second input signal to generate an output signal. The pre-distortion parameters generating circuit generates the first pre-distortion parameters and the second pre-distortion parameters according to the first input signal, the second input signal and the output signal.