DPD Linearization for RF Power Amplifier Memory Effects
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Solution Overview
Problem
Existing power amplifier architectures in wireless communication systems face challenges in achieving both linearity and efficiency due to inherent non-linearity of active devices, particularly in high frequency, high power applications with multiple energy storage elements, which requires computational resource-intensive correction of electrical memory effects.
Innovation Solution
A wireless communication unit with a digital predistortion (DPD) architecture that includes a feedback path to route memory effect information back to the DPD processor, using a Hall effect element to provide envelope current information and a voltage-controlled resistor to dampen resonance, allowing for improved DPD correction and reduced algorithm complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If digital predistortion is used to correct electrical memory effects, then linearity is improved, but computational resource consumption increases
Solution Approach 1:
The patent applies preliminary action by measuring and storing the state of energy storage elements (capacitor voltages and inductor currents) before they affect the power amplifier output. These pre-measured states are then used by the DPD algorithm to compensate for memory effects, reducing the computational burden of real-time correction while maintaining linearity.
Solution Approach 2:
The patent introduces intermediary measurement circuits (voltmeter for capacitor voltage, ammeter for inductor current) that act as mediators between the energy storage elements and the DPD processor. These intermediaries convert physical states into measurable signals that can be processed with reduced computational complexity.
2Loss of energy
If multiple energy storage elements are used in power amplifier, then efficiency is improved, but electrical memory effects increase requiring complex correction
Solution Approach 1:
The patent segments the electrical memory effects into individual contributions from each energy storage element (capacitor C1, capacitor C2, inductor L1). By measuring and correcting each element's effect separately through dedicated measurement circuits, the overall correction complexity is reduced while maintaining the efficiency benefits of multiple energy storage elements.
Solution Approach 2:
The patent implements feedback by routing measurements of capacitor voltages and inductor currents back to the DPD processor. This feedback mechanism provides the processor with real-time information about the state of energy storage elements, enabling accurate compensation of their memory effects without requiring complex computational models.
3Productivity
If computational resources are reduced for DPD correction, then algorithm complexity decreases, but measurement precision requirements increase
Solution Approach 1:
The patent applies self-service by having the measurement circuits directly integrated with the energy storage elements they monitor. The voltmeter measures capacitor voltage and the ammeter measures inductor current at their respective locations, providing self-contained measurement systems that reduce the precision burden on the DPD processor by capturing signals close to their source.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enhances the linearity and efficiency of power amplifiers by accurately correcting electrical memory effects, reducing computational resources needed and improving DPD algorithm complexity, especially in wide bandwidth signals.
Implementation Method 1
using a Hall effect element to provide envelope current information
Implementation Method 2
a voltage-controlled resistor to dampen resonance
Data Source
AI summary
A wireless communication unit comprising a transmitter comprises: a linearization circuit arranged to receive and digitally distort an input signal; a radio frequency power amplifier operably coupled to the linearization circuit and arranged to amplify a radio frequency representation of the digitally distorted input signal; a feedback path arranged to feed back a portion of the amplified digitally distorted output of the received input signal to the linearization circuit; a bypass circuit comprising a plurality of energy storage elements operably coupled between an output of the radio frequency power amplifier and ground; and a first connector arranged to provide a representation of at least one electrical memory effect of at least one of the plurality of energy storage elements to the linearization circuit, wherein the linearization circuit is arranged to use the representation of the at least one electrical memory effect when digitally distorting the input signal.