Configurable DPD Non-Linear Filter for Charge Trapping Compensation
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Solution Overview
Problem
Radio transceivers face challenges in compensating for transient non-ideal behaviors in power amplifiers, particularly due to charge trapping effects, which affect device characteristics and lead to performance issues such as transconductance frequency dispersion and current collapse.
Innovation Solution
A digital pre-distortion (DPD) system with a configurable non-linear filter, such as a Laguerre filter, is employed to account for charge trapping effects by decimating incoming data using various decimation ratios and providing it to rows with configurable coefficients, allowing for flexible compensation across different time ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed non-linear filter is used for digital pre-distortion, then the circuit complexity is reduced, but the ability to compensate for charge trapping effects across different time ranges is limited
Solution Approach 1:
The patent implements a non-linear filter where the decimation ratio is dynamically configurable based on the time range of charge trapping effects that need to be compensated. Different decimation ratios (e.g., 1, 2, 4, 8) can be selected to match different charge trapping time constants, allowing the filter to adapt its behavior to different operational conditions while maintaining a single physical filter structure.
Solution Approach 2:
The patent changes the decimation ratio parameter of the non-linear filter to match different charge trapping time constants. By adjusting this single parameter, the filter can effectively compensate for charge trapping effects occurring at different time scales without requiring multiple separate filter circuits, thus resolving the contradiction between adaptability and complexity.
2Adaptability or versatility
If multiple fixed non-linear filters with different time constants are used, then charge trapping effects across different time ranges can be compensated, but the device complexity increases
Solution Approach 1:
The patent designs a single non-linear filter circuit that can perform multiple compensation functions by changing its decimation ratio. This universal filter can compensate for charge trapping effects across the entire time range (from microseconds to milliseconds) by selecting appropriate decimation ratios, eliminating the need for multiple separate filter circuits and thereby reducing device complexity while maintaining comprehensive coverage.
3Adaptability or versatility
If a high decimation ratio is used in the non-linear filter, then charge trapping effects with longer time constants can be compensated, but the processing speed of the DPD system decreases
Solution Approach 1:
The patent dynamically selects the decimation ratio based on the specific charge trapping time constant that needs to be compensated. When long time constant compensation is required, a higher decimation ratio is selected; when shorter time constant compensation is needed, a lower decimation ratio is used. This dynamic adaptation allows the system to optimize between compensation effectiveness and processing speed depending on the operational conditions.
Data Source
AI summary
Some embodiments herein describe a radio frequency communication system that can include a transmitter to output an radio frequency (RF) transmit signal, the transmitter including a digital pre-distortion system (DPD) that pre-distorts the RF transmit signal. The DPD system can include a configurable non-linear filter, such as a Laguerre filter, having multiple rows where at least one row operates with a configurable decimation ratio. The DPD system can further include decimators and a crossbar switch coupled between the decimators.