Phased Array Feedback Coupling for Beam-Angle DPD Linearization
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Solution Overview
Problem
In active phased arrays for 5G millimeter wave systems, Power Amplifiers face beamsteering angle-dependent load modulation due to lack of space for circulators, necessitating adaptive Digital Pre-Distortion (DPD) to linearize phased array beam output rather than individual PA outputs, while conventional systems suffer from insertion loss reducing overall transmit efficiency.
Innovation Solution
A wireless communication system incorporating a phased array with directional couplers and switching circuitry to extract forward and reflected power, allowing DPD to be adjusted for beamsteering angles, thereby mitigating load modulation and omitting the need for isolators, which reduces insertion loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolator is inserted between antenna and PA output to linearize the PA, then the DPD can be implemented, but the insertion loss significantly reduces the overall transmit efficiency
Solution Approach 1:
The patent extracts the linearization function from the traditional isolator-DPD approach and implements it directly through DPD circuitry that processes the PA output signal. By taking out the isolator component and using signal processing instead, the system achieves PA linearization without the insertion loss penalty of physical isolators.
Solution Approach 2:
The patent replaces the mechanical/electromagnetic isolator with a digital signal processing system. Instead of using physical components to achieve linearization, the system uses digital algorithms to process and correct the PA output, substituting a mechanical approach with an information-processing approach that has no insertion loss.
2Use of energy by moving object
If DPD is adapted for each single PA output, then the PA efficiency can be improved, but the phased array beam output cannot be linearized due to angle-dependent load modulation
Solution Approach 1:
The patent merges the individual PA DPD functions into a unified phased-array-level DPD system. Instead of treating each PA independently, the system combines their outputs and applies a single DPD function that accounts for the collective beamforming characteristics and angle-dependent load modulation, thereby achieving both efficiency and linearity.
Solution Approach 2:
The patent implements a dynamic DPD system that adapts to changing beamsteering angles and load conditions. The DPD parameters are adjusted in real-time based on the actual operating conditions of the phased array, allowing the system to maintain optimal performance across different beam directions and load scenarios.
3Reliability
If circulators are inserted to handle load modulation, then the PA can be protected, but there is lack of space in mmWave systems
Solution Approach 1:
The patent extracts the PA protection function from the circulator component and implements it through digital signal processing. By removing the physical circulator and using DPD to manage reflected power and load modulation effects, the system achieves PA protection without requiring additional space for isolators or circulators.
Solution Approach 2:
The patent uses virtual modeling and digital representation of the PA load conditions to simulate and manage reflected power effects. Instead of physically diverting reflected power with circulators, the system creates a digital model of the load and uses this information to adjust the PA operation, effectively copying the protection function in the digital domain rather than requiring physical components.
Data Source
AI summary
A wireless communication system including a phased array comprising a plurality of antennas configured to emit a respective radio wave based on a respective antenna signal. Further, the system includes a plurality of power amplifiers each coupled to one of the plurality of antennas via a feed line and configured to output the antenna signal to the feed line. Also, the system includes a plurality of directional couplers each coupled into one of the feed lines and comprising a third port configured to output a fraction of a power received at a first port coupled to the power amplifier via the feed line, likewise a fourth port configured to output a fraction of a power received at a second port. Additionally, the system includes switching circuitry configured to alternately couple the third port to a first feedback receiver, and to alternately couple the fourth port to a second feedback receiver.