Self-Calibrating Vector Network Analyzer with Internal Impedance Module
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Solution Overview
Problem
Existing vector network analyzer calibration methods require external standards and are not suitable for portable instrumentation due to the need for periodic recalibration in varying environments, limiting their accuracy and convenience.
Innovation Solution
Incorporating a multi-state impedance module inside the network analyzer behind each test port, allowing for automatic self-calibration using characterized internal standards, eliminating the need for external calibration kits and enabling full two-port calibrations for both insertable and non-insertable measurements without additional standards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional external calibration standards are used, then measurement accuracy is maintained, but device complexity and portability are reduced
Solution Approach 1:
The patent combines the calibration standards and the measurement device into a single integrated unit. The synthesizer generates calibration signals directly within the measurement device, eliminating the need for separate external calibration standards. This merging maintains measurement accuracy while reducing device complexity and improving portability.
Solution Approach 2:
The synthesizer serves multiple functions: it generates calibration signals for error correction and also provides signal generation for normal measurements. This multi-functionality eliminates the need for separate calibration equipment, reducing overall system complexity while maintaining accuracy.
2Measurement precision
If external calibration kits are required, then calibration accuracy is ensured, but ease of operation and productivity are reduced
Solution Approach 1:
The measurement device performs its own calibration using internally generated signals from the synthesizer. The device automatically generates calibration standards, measures them, and corrects systematic errors without requiring external calibration kits or manual intervention. This self-service approach ensures calibration accuracy while dramatically improving ease of operation.
Solution Approach 2:
The synthesizer pre-generates calibration signals at known impedance states (e.g., 50 ohms, 75 ohms, 100 ohms) before measurements are taken. These preliminary calibration signals enable the device to automatically determine and correct systematic errors, ensuring accurate measurements without requiring external calibration equipment during operation.
3Measurement precision
If full 2-port calibration is performed with external standards, then transmission error coefficients are obtained, but loss of time and productivity increase
Solution Approach 1:
The synthesizer continuously generates calibration signals and the device continuously performs error correction calculations during normal operation. Rather than requiring a separate calibration phase, the calibration process occurs continuously in the background, eliminating calibration downtime and maintaining measurement accuracy throughout operation.
Solution Approach 2:
The patent replaces mechanical calibration procedures (physical connection of external calibration standards) with electronic signal generation from the synthesizer. This substitution eliminates the time-consuming mechanical steps of connecting and disconnecting external calibration kits, dramatically reducing calibration time while maintaining full 2-port calibration accuracy.
4Adaptability or versatility
If portable instrumentation is used, then ease of operation and adaptability improve, but measurement precision deteriorates due to environmental conditions
Solution Approach 1:
The device uses feedback from measuring internally generated calibration signals to continuously monitor and correct for environmental variations. The synthesizer generates known reference signals that pass through the same environmental conditions as external measurements, allowing the device to detect and compensate for temperature drift, humidity effects, and other environmental factors that affect portability.
Data Source
AI summary
In one method of calibrating an instrument having N ports, where N>=2, cables of a first type are characterized by connecting a first cable between two of the ports; performing an “unknown-thru” full two-port calibration between the two ports; obtaining a S-parameter of the first cable; saving the S-parameter of the first cable; and then repeating the connecting, performing, obtaining and saving for additional cables having the first type. The cables having the first type are then disconnected from one of the two ports and a measurement plane is transferred from the connected end of the cable to the disconnected end of the cable. Cables of a second type are then characterized by connecting a second cable between the second of the two ports and the disconnected end of the first cable; measuring a S-parameter of the second cable; and saving the S-parameter of the second cable.