Quadrature Power Amplifier Detection With Load-Insensitive Phase Combining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Dual detector arrangements in quadrature power amplifiers exhibit errors at load phase angles other than 90 and 270 degrees, and these errors worsen with increasing voltage standing wave ratio (VSWR), leading to inaccurate power detection and artificially lowered output power in closed loop power control systems.
Innovation Solution
Implementing a phase shift element to shift the phase of input signals from both amplification paths, combining these shifted signals, and using a single power detector to determine the power of the combined signal, thereby minimizing errors caused by varying load phase angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a dual detector arrangement is used to sample power in in-phase and quadrature paths, then power detection capability is provided, but detector error occurs at load phase angles other than 90 and 270 degrees
Solution Approach 1:
The patent combines the in-phase and quadrature path signals through phase shifting elements and a combiner to create a single-phase signal that is then detected by a single power detector. This merging approach eliminates the directional sensitivity issues of dual detectors while maintaining power detection capability across all load phase angles.
Solution Approach 2:
The patent changes the phase parameter of the input signals using phase shift elements before combining them. By adjusting the phase of the in-phase and quadrature signals, the system transforms the signal representation to enable accurate power detection regardless of the original load phase angle, effectively decoupling detection accuracy from load phase dependencies.
2Measurement precision
If a dual detector arrangement is used, then power detection is enabled, but error worsens as voltage standing wave ratio (VSWR) increases
Solution Approach 1:
By merging the in-phase and quadrature signals into a single-phase combined signal before detection, the system eliminates the directional sensitivity that causes VSWR-dependent errors in dual detector arrangements. The single power detector processes the combined signal without being affected by load phase or VSWR variations.
3Measurement precision
If a single element power detector is used with phase shifted combined signals, then accurate power detection is achieved regardless of load phase angle, but additional phase shift elements and combiner are required
Solution Approach 1:
The patent uses phase shift elements to transform the phase parameters of the in-phase and quadrature signals, enabling their constructive combination into a single-phase signal. This parameter transformation approach achieves load-insensitive power detection using a single detector element, balancing the trade-off between accuracy and complexity.
Data Source
AI summary
A power detector includes a first phase shift element implemented to shift a phase of a first input signal to generate a first phase-shifted signal, a second phase shift element implemented to alter a phase of a second input signal to generate a second phase-shifted signal, a combiner for combining the first phase-shifted signal and the second phase-shifted signal to generate a combined single-phase signal, and a single element power detector for determining a power of the combined single-phase signal.