Variable-Bit Distortion Compensation Circuit for Amplifier Linearity
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Solution Overview
Problem
Power amplifiers in radio communication systems face challenges with non-linear distortion, leading to inefficient operation and signal distortion due to varying characteristics and bit format limitations in digital pre-distortion schemes, which require frequent circuit adjustments and result in inaccurate signal representation.
Innovation Solution
A distortion compensation circuit that dynamically adjusts the bit format based on the amplifier's characteristics, calculating distortion compensating coefficients to perform distortion compensation using a variably set bit format, ensuring accurate representation and minimizing circuit modifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed bit format is used in digital pre-distortion, then circuit complexity is reduced, but manufacturing precision deteriorates due to saturation and inaccurate signal representation
Solution Approach 1:
The patent applies dynamics by making the bit format variable rather than fixed. The distortion compensation circuit dynamically adjusts the bit format based on the input signal characteristics and amplifier operating conditions. This allows the system to optimize between circuit complexity and signal accuracy in real-time, avoiding saturation while maintaining reasonable computational load.
Solution Approach 2:
The patent changes the parameter of bit format (number of bits, fixed-point position) adaptively. By varying these parameters according to signal conditions, the system achieves high precision signal representation when needed while avoiding unnecessary complexity when the signal conditions permit simpler formats.
2Manufacturing precision
If the number of bits is increased to improve expression accuracy, then manufacturing precision improves, but device complexity increases due to larger circuit size and higher cost
Solution Approach 1:
The system dynamically adjusts the number of bits used in distortion compensation based on actual signal conditions. When high precision is required (e.g., during high-power operation or with complex modulation), more bits are allocated. During low-power or simpler conditions, fewer bits suffice, reducing circuit complexity and cost while maintaining adequate precision.
Solution Approach 2:
The patent varies the bit depth and fixed-point position parameters adaptively. This allows the system to achieve high expression accuracy when necessary while avoiding the constant overhead of high-precision arithmetic in all operating conditions, thus optimizing the trade-off between precision and circuit complexity.
3Manufacturing precision
If different lookup tables are used for large and small signal regions, then manufacturing precision improves by enlarging dynamic range, but device complexity increases due to multiple tables and switching logic
Solution Approach 1:
The patent creates a universal distortion compensation method that works across the entire signal range by using variable bit formats. Instead of requiring separate lookup tables for different signal regions, the single compensation algorithm adapts its precision and range through dynamic bit format adjustment, achieving multi-functionality without the complexity of multiple specialized components.
Solution Approach 2:
The system dynamically adjusts the bit format to accommodate different signal regions (large and small signals) within a single unified lookup table or compensation algorithm. This eliminates the need for switching between multiple static tables, reducing circuit complexity while maintaining the ability to handle the full dynamic range with appropriate precision.
Data Source
AI summary
A distortion compensation circuit for compensating for the distortion characteristics of an amplifier, includes a distortion compensating coefficient calculating element and a distortion compensating operation element. The distortion compensating coefficient calculating element calculates a distortion compensating coefficient to be used for compensation of the distortion characteristics by comparing an input signal with the output signal amplified by the amplifier. The distortion compensating operation element performs a distortion compensating operation on the input signal, using a variably set bit format and the distortion compensating coefficient calculated by the distortion compensating coefficient calculating element.