Analog Predistortion Circuit for Power Amplifier Distortion Normalization
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Power amplifiers in mobile communication devices face challenges in maintaining linear operation at high frequencies, leading to signal distortion and the need for unique predistortion profiles for each device, which increases testing time and costs.
Innovation Solution
An analog predistortion (APD) circuit is introduced to normalize the distortion profile of power amplifiers, allowing for a single set of digital predistortion (DPD) coefficients to be used across multiple devices, reducing the need for customized testing and coefficients.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital predistortion is applied to each power amplifier individually to correct distortion, then linear operation is improved, but testing time and manufacturing costs increase
Solution Approach 1:
The patent changes the distortion profile parameters of the power amplifier from device-specific to normalized by introducing an analog predistortion circuit that applies fixed compensation values, eliminating the need for individual device characterization and calibration
Solution Approach 2:
The patent creates a standardized distortion profile model that can be copied and applied across multiple power amplifiers through the APD circuit, replacing the need for unique per-device digital predistortion profiles
2Reliability
If unique predistortion profiles are generated for each power amplifier to maintain linearity, then signal quality is improved, but manufacturing complexity and costs increase
Solution Approach 1:
The patent transforms the manufacturing approach by changing the distortion compensation parameters from variable (device-specific) to fixed (normalized), allowing standardized production without individual device calibration
Solution Approach 2:
The patent extracts the distortion compensation function from the complex digital predistortion system and implements it through a simpler analog predistortion circuit with fixed parameters, reducing manufacturing complexity
3Manufacturing precision
If device-specific calibration is performed to optimize predistortion coefficients, then performance is improved, but production time and costs increase
Solution Approach 1:
The patent changes the calibration parameters from device-specific optimized values to normalized fixed values that provide sufficient performance across all devices without requiring individual optimization
Solution Approach 2:
The patent performs distortion normalization in advance through the APD circuit before digital predistortion is applied, eliminating the need for subsequent per-device calibration steps and enabling immediate production
Data Source
AI summary
An analog predistortion (APD) circuit is disclosed. In one aspect, the power amplifier is in a front-end module (FEM) of a radio frequency transceiver. An APD circuit operates within an amplifier chain to normalize the distortion of the amplifier chain. A baseband processor (BBP) performs digital predistortion (DPD) on signals being sent from the BBP to the FEM. As a result of the APD, the DPD may assume a normalized profile for the FEM, allowing for simplification of the DPD despite many possible distortions introduced by the amplifier chain.