Load Pull Pattern Generation via Frequency Sweeping
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Solution Overview
Problem
Existing load and source pull techniques using mechanical tuners are slow due to the mechanical probe movement required to change the phase of the reflection factor, taking several seconds per impedance point, especially at lower frequencies.
Innovation Solution
The method employs slide screw tuners, utilizing the natural behavior of reflection factor rotation with frequency and quasi-constant amplitude over large frequency bands, allowing phase changes by adjusting the measurement frequency instead of moving the tuner, and using vertical movements to create concentric circles, reducing measurement time significantly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If mechanical probe movement is used to change the phase of the reflection factor, then the impedance points can be measured, but the measurement time becomes very long (several seconds per impedance point)
Solution Approach 1:
The patent changes the operating frequency parameter of the DUT to induce rotation of the reflection factor on the Smith chart, eliminating the need for slow mechanical probe movement. By sweeping frequency, the method achieves phase changes of the reflection factor rapidly, reducing measurement time from several seconds per point to much faster rates while maintaining measurement precision.
Solution Approach 2:
The patent replaces the mechanical probe movement system with an electrical frequency control system. Instead of physically moving the probe to change impedance points, the method uses frequency modulation of the DUT to achieve the same effect, substituting mechanical action with electrical control for dramatically improved speed.
2Ease of operation
If horizontal probe movement along the transmission line is used to change the phase, then the reflection factor phase can be adjusted, but the measurement process becomes slow (up to 15 seconds at lower frequencies)
Solution Approach 1:
The patent changes the frequency parameter to control the phase of the reflection factor instead of moving the probe horizontally. The phase φ is controlled by the electrical length which varies with frequency, allowing rapid phase adjustment through frequency modulation rather than slow mechanical translation.
Solution Approach 2:
Instead of moving the probe to change phase (traditional approach), the patent inverts the approach by changing frequency to achieve phase change. This reversal of the control mechanism transforms a slow mechanical process into a fast electrical control process.
3Measurement precision
If the tuning probe is moved horizontally to create impedance patterns, then the load pull contours can be measured, but the process takes several seconds per impedance point
Solution Approach 1:
The patent uses frequency sweeping to generate the impedance patterns needed for load pull measurements. By varying frequency, the reflection factor traces out the necessary patterns on the Smith chart without mechanical probe movement, maintaining measurement precision while dramatically increasing the data collection rate.
Solution Approach 2:
The patent replaces the mechanical impedance tuning system with an electrical frequency modulation system. The impedance patterns required for load pull contours are generated through frequency variation rather than physical probe movement, substituting mechanical complexity and slowness with electrical simplicity and speed.
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 reduces measurement time from minutes to seconds by eliminating the need for horizontal tuner movement, enabling faster data collection for RF ISO contours without compromising accuracy.
Implementation Method 1
the natural behavior of slide screw tuners, of which the reflection factor Γ=|Γ|*exp(jΦ) rotates fast with frequency, due to the long transmission lines between tuning probe and DUT
Implementation Method 2
the reflection factor Γ=|Γ|*exp(jΦ) rotates fast with frequency, due to the long transmission lines between tuning probe and DUT
Data Source
AI summary
A method for instantaneous load pull impedance pattern generation uses a phase-frequency-location equivalent of the natural behavior of slide screw tuners to skew the reflection factor phase with only small frequency changes. The method is generic and applies the same to all GHz range test frequencies. A simple calculation determines the tuning probe position and the impedance cloud is generated quasi instantaneously by switching between sidebands of the carrier test frequency without mechanically moving the tuning probe. Benign frequency behavior of the tuners allows for simple and accurate narrowband interpolation. Duration of load pull measurements is reduced from minutes to seconds.