Network Analyzer Group Delay Measurement Using Two-Tone Signals
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Solution Overview
Problem
Current methods for measuring group delay in electronic components are hindered by additional influencing factors such as phase-distorting effects from leads and unknown oscillator frequencies, requiring complex equipment and calibration processes.
Innovation Solution
A network analyzer generates a harmonic two-tone signal and measures the phase difference between excitation and response signals, allowing for the calculation of group delay without the need for additional calibration, thereby compensating for unknown oscillator frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional group delay measurement methods are used with amplitude-modulated excitation signals and Dirac comb generation, then group delay can be determined, but the equipment complexity increases significantly requiring signal generators, transient recorders, spectrum analyzers, and synchronization devices
Solution Approach 1:
The patent combines the excitation signal generation and response signal measurement into a single network analyzer system. The network analyzer simultaneously generates the two-tone excitation signal and measures both the excitation and response signals through its measurement and reference channels, eliminating the need for separate signal generators, transient recorders, and spectrum analyzers required by conventional methods
Solution Approach 2:
The network analyzer performs multiple functions: it generates the two-tone excitation signal, measures the response signal from the DUT, measures the reference excitation signal, and processes both signals to determine group delay. This multi-functional approach replaces the specialized equipment chain needed in conventional measurement methods
2Measurement precision
If conventional measurement methods are used, then group delay can be measured, but additional calibration measurements at reference carrier frequencies are required to compensate for unknown phase of modulation signals
Solution Approach 1:
The patent uses the reference channel to create a copy of the excitation signal that bypasses the DUT. By measuring this reference signal simultaneously with the response signal and comparing their phases, the system automatically compensates for oscillator frequency variations and phase distortions without requiring separate calibration measurements
Solution Approach 2:
The system uses the reference signal as a feedback reference to continuously monitor and compensate for phase variations in the measurement process. The phase difference between the reference and response signals provides real-time compensation for oscillator drift and system phase distortions
3Measurement precision
If Dirac comb generation is used for excitation, then group delay measurement is possible, but the generation process becomes complex
Solution Approach 1:
Instead of generating a complex Dirac comb signal, the patent changes the excitation signal parameters to use a simple harmonic two-tone signal with defined frequency spacing. This parameter change simplifies the signal generation process while maintaining the ability to measure group delay through phase difference analysis of the sideband components
Data Source
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AI summary
A network analyser for measuring a group runtime (T G ), generated by a measuring object (17) to be measured, generates a stimulating signal (x ln (t)) made up of two signals (x In1 (t), x In2 (t)) separated by a frequency difference (??) stimulates the measuring object with the stimulating signal (x In (t)) and measures a response signal (x Out (t)) made up of two signals (x Out1 (t), x Out2 (t)), which are phase shifted by the measuring object (17) relative to the signals (x In1 (t), x In2 (t)) of the stimulation signal (x In (t)). The analyser then determines the phase difference (?f In ) between the signals (x In1 (t), x In2 (t)) of the stimulation signal (x In (t)) and a phase difference (?f Out ) between the against (x Out1 (t), x Out2 (t)) of the response signal (x Out (t)). The analyser finally calculates the group runtime (T G ) from the phase difference (?f In ) of the signals (x In1 (t), x In2 (t)) belonging to the stimulation signal (x In (t)) the phase difference (?f Out ) of the signals (x Out1 (t), x Out2 (t)) belonging to the response signal (x Out (t)) and the frequency separation (??).