DPD Signal Classification Using Multi-Path Frequency Metrics
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Solution Overview
Problem
Existing digital pre-distortion (DPD) circuits struggle to maintain optimal performance due to changes in input signal properties, such as power and frequency, leading to less-than-satisfactory linearity in transmitter power amplifiers.
Innovation Solution
An apparatus and method for signal classification in DPD circuits, utilizing multiple frequency paths with filters and a processing unit to compute frequency content metrics, including half-band power ratio and bandwidth metrics, for selecting optimal DPD coefficients, which are mapped in a three-dimensional or two-dimensional space to configure the DPD circuit effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If filter coefficients for the DPD circuit are configured based on certain properties (power and frequency) of the input signal, then the DPD circuit can achieve satisfactory performance under those conditions, but when those properties change, the DPD circuit no longer yields satisfactory performance
Solution Approach 1:
The patent implements dynamic adaptation by continuously monitoring signal properties (power, frequency, bandwidth) and updating DPD filter coefficients in real-time based on current signal conditions. This allows the system to transition from static pre-configured coefficients to dynamic adaptive coefficients that respond to changing signal characteristics, resolving the contradiction between reliability under fixed conditions and adaptability to changing conditions.
Solution Approach 2:
The system employs feedback mechanisms where the actual signal properties are measured and used to adjust the DPD coefficients. The error between desired and actual output is fed back to update the filter coefficients, enabling the system to maintain optimal performance across varying signal conditions by continuously learning and adapting to new signal characteristics.
2Measurement precision
If multiple frequency paths with filters are used to compute frequency content metrics for selecting DPD coefficients, then frequency selectivity and pre-distortion performance are improved, but device complexity increases
Solution Approach 1:
The patent segments the frequency analysis into multiple parallel paths, each dedicated to measuring specific frequency content metrics (power, bandwidth, spectral characteristics). By dividing the complex measurement task into smaller specialized sub-tasks handled by separate filter paths, the system achieves high measurement precision while organizing complexity into manageable modular components that can be independently optimized.
Data Source
AI summary
A circuit for signal classification in a digital pre-distortion (DPD) system is provided. The circuit includes a first frequency path with a positive frequency translation to generate a first power level corresponding to a signal output of the first frequency path, a second frequency path with a negative frequency translation to generate a second power level corresponding to a signal output of the second frequency path, and a third frequency path configured to filter the input signal via a high pass filter (HPF) and to generate a third power level corresponding to a signal output of the third frequency path. The circuit further includes a processing unit configured to compute frequency content metrics corresponding to the input signal based on the first power level, the second power level and the third power level for selecting a set of DPD coefficients for the DPD circuit.