Group Delay Measurement Using Amplitude Modulation
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Solution Overview
Problem
Existing methods for measuring group delay require two separate sources and external components, limiting the usability of measurement devices and setups, as they necessitate the use of combiners or couplers to combine signals, occupying multiple ports and restricting further measurements.
Innovation Solution
A method involving amplitude modulation of a test signal with a carrier frequency to generate symmetrical group delay signals, utilizing a high-speed voltage controlled attenuator to produce sideband signals, allowing for multi-tone stimulation with a single source and port, enabling simultaneous measurement of group delay and scattering parameters without additional hardware.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two different sources are used to generate a two-tone stimulus signal for group delay measurement, then the measurement accuracy is improved, but the usability of the measurement device is reduced due to occupying two ports
Solution Approach 1:
The patent combines two separate signal sources into a single source by using amplitude modulation on a carrier signal to generate the two-tone stimulus. The modulator merges the functionality of two independent sources into one, allowing both tones to be generated from a single oscillator through modulation, thus occupying only one port while maintaining measurement accuracy
Solution Approach 2:
The single signal source is designed to perform multiple functions: it generates the carrier signal and simultaneously produces the two-tone stimulus through amplitude modulation. This multi-functional approach allows one source to replace two separate sources, improving device usability while maintaining measurement capability
2Measurement precision
If an external combiner or coupler is used to combine signals from two sources, then the two-tone stimulus is generated, but the device complexity increases and ports are occupied
Solution Approach 1:
The patent eliminates the need for external combiners or couplers by integrating the signal combination function directly into the modulation process. The modulator internally combines the carrier and modulation signals to produce the two-tone output, removing external hardware requirements and simplifying the measurement setup
Solution Approach 2:
The measurement device performs the signal combination function itself through internal modulation circuitry, rather than requiring external辅助设备. The single source self-generates the two-tone stimulus through amplitude modulation, making the system self-sufficient and reducing external hardware dependencies
3Measurement precision
If high power stimulus signals are used for group delay measurement, then the measurement sensitivity is improved, but the risk of damaging sensitive devices under test increases
Solution Approach 1:
The patent employs dynamic control of stimulus power through amplitude modulation, allowing the power level to be adjusted in real-time based on device sensitivity requirements. The modulation depth and carrier power can be dynamically adapted to provide sufficient signal strength for measurement while staying within safe limits for sensitive devices
Solution Approach 2:
The system changes the power parameter of the stimulus signal by controlling modulation depth and carrier amplitude. This allows flexible adjustment of stimulus power to match the specific requirements of different devices under test, optimizing both measurement sensitivity and device safety
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 increases the usability of measurement devices by allowing group delay measurements with a single source and port, doubling measurement speed while minimizing stimulation for sensitive devices and ensuring symmetry and sensitivity adjustments, thus optimizing device testing.
Implementation Method 1
applying an amplitude modulation to the test signal in order to generate at least two group delay signals having frequencies that are symmetrical to the frequency of the test signal
Implementation Method 2
the amplitude modulation is done by using an attenuator or a modulator, in particular a high speed voltage controlled attenuator
Data Source
AI summary
A method for measuring group delay on a device under test is described, wherein a test signal with a carrier frequency is generated. An amplitude modulation is applied to said test signal in order to generate at least two group delay signals having frequencies that are symmetrical to the frequency of said test signal. At least said group delay signals are provided to said device under test. Further, a measurement device and a measurement system are described.