Phase Difference Detection for RF Impedance Mismatch Compensation
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Solution Overview
Problem
Impedance mismatch between a power amplifier and an antenna in wireless communication devices, caused by external metallic objects, leads to reduced power amplifier linearity, RF output power, and efficiency, and existing solutions like isolators add weight and cost or reduce transmitted power.
Innovation Solution
A phase difference detection apparatus that uses directional couplers, phase shifters, combiners, detectors, and adjustment circuitry to detect and adjust the phase difference between incident and reflected signals, compensating for impedance mismatches without affecting power amplifier linearity or efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an isolator is added at the output of the power amplifier to absorb reflected power, then the power amplifier linearity is improved, but the device size and weight increase
Solution Approach 1:
The patent extracts only the essential function of the isolator (managing reflected power) and implements it through a compact detection apparatus that monitors phase difference between incident and reflected signals. This allows the system to address impedance mismatch issues without incorporating a full-sized isolator, thereby reducing device weight while maintaining power amplifier linearity.
Solution Approach 2:
The patent introduces a phase difference detection apparatus as an intermediary between the power amplifier and antenna system. This intermediary component provides real-time monitoring and detection of reflected power characteristics, enabling the system to manage impedance mismatch effects without requiring a bulky isolator, thus resolving the contradiction between reliability and weight.
2Reliability
If an isolator is added at the output of the power amplifier to absorb reflected power, then the power amplifier linearity is improved, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the essential monitoring function from the complex isolator system and implements it through a simplified detection apparatus that measures phase difference between incident and reflected signals. This extraction approach maintains power amplifier linearity while significantly reducing device complexity and cost compared to using a full isolator.
Solution Approach 2:
The patent creates a simplified model or representation of the reflected power management function through phase difference detection. Instead of implementing the full isolator hardware, the system uses detection circuitry that copies or simulates the essential monitoring capability, thereby reducing complexity while achieving the same reliability benefit.
3Reliability
If the drive level at the input of the power amplifier is reduced to reduce output voltage swing, then the impedance mismatch effects are mitigated, but the transmitted RF output power is significantly reduced
Solution Approach 1:
The patent implements a feedback mechanism through phase difference detection between incident and reflected signals. By continuously monitoring the phase difference, the system can detect impedance mismatch conditions and provide feedback to adjust operating parameters. This allows the power amplifier to maintain optimal drive levels for high output power while compensating for mismatch effects, resolving the contradiction between reliability and transmitted power.
Solution Approach 2:
The patent changes the monitoring parameter from direct voltage swing measurement to phase difference detection. By detecting phase difference between incident and reflected signals, the system can identify mismatch conditions without requiring reduction of the drive level. This parameter change enables the system to maintain high transmitted RF output power while still mitigating impedance mismatch effects through appropriate compensation.
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
The solution effectively compensates for impedance mismatches, improving system performance by adjusting the phase difference to optimize power transmission without significant impact on power amplifier linearity or efficiency, thus enhancing the overall efficiency and performance of wireless communication devices.
Implementation Method 1
a first representation of the incident signal and a second representation of the reflected signal are received from a directional coupler
Implementation Method 2
a plurality of phase shifters adapted to apply first phase shifts to the first representation of the incident signal and to the second representation of the reflected signal in order to produce a plurality of first phase shifted signals
Data Source
AI summary
Embodiments include methods and apparatus for detecting a phase angle between an incident signal and a reflected signal. The apparatus comprises a plurality of phase shifters and additional circuitry. The plurality of phase shifters is adapted to apply first phase shifts to a representation of the incident signal and to apply second phase shifts to a representation of the reflected signal. The additional circuitry, which is operatively coupled to the plurality of phase shifters, is adapted to produce a first indication of a location of a relative phase difference between the incident signal and the reflected signal within a first region of a first reference circle, and to produce a second indication of the location of the relative phase difference within a second region of a second reference circle, wherein the second reference circle is rotated with respect to the first reference circle.