Network Analyzer Noise Figure Measurement
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Solution Overview
Problem
Current methods for measuring the noise figure of a device under test require multiple instruments, including a network analyzer for S-parameters and a spectrum analyzer for noise power, which is inefficient and prone to inaccuracies due to the need for a noise source and complex calibration processes.
Innovation Solution
A method using a network analyzer with input sensitivity equivalent to a spectrum analyzer to measure S-parameters and output noise power without a noise source, incorporating a calibration process to correct for internal noise and impedance errors, allowing for the determination of noise figure using a single instrument.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a network analyzer and spectrum analyzer are used together to measure noise figure, then measurement accuracy is improved, but device complexity and cost increase
Solution Approach 1:
The patent combines the functions of the network analyzer and spectrum analyzer into a single network analyzer. The network analyzer is configured to measure both S-parameters (for power amplification calculation) and output noise power, eliminating the need for a separate spectrum analyzer. This merging of measurement functions directly reduces device complexity while maintaining measurement capability.
Solution Approach 2:
The network analyzer is enhanced to perform multiple measurement functions: it measures S-parameters for determining power amplification, measures output noise power of the DUT, and performs calibration measurements. This multi-functionality allows a single instrument to replace what previously required two separate instruments, resolving the contradiction between measurement precision and device complexity.
2Measurement precision
If a noise source is used to excite the DUT for noise figure measurement, then noise power measurement is improved, but measurement structure complexity increases
Solution Approach 1:
The patent extracts and removes the noise source from the measurement system. Instead of using an external noise source to excite the DUT, the method measures the output noise power of the DUT directly when it is operating in its normal state. This extraction of the noise source simplifies the measurement structure while maintaining the ability to measure noise figure through alternative measurement approaches.
Solution Approach 2:
The DUT itself serves as the noise source by measuring its own output noise power. The network analyzer measures the noise power that the DUT inherently generates and outputs, without requiring external noise excitation. This self-service approach eliminates the need for additional noise source equipment and simplifies the overall measurement configuration.
3Measurement precision
If error matching correction is applied for impedance mismatch, then measurement accuracy is improved, but calibration complexity increases
Solution Approach 1:
The patent performs calibration measurements in advance to determine error-matching factors before actual noise figure measurements. The calibration process involves measuring the network analyzer's input impedance characteristics and calculating correction factors that are stored and applied during subsequent measurements. This preliminary action ensures measurement accuracy is improved through error correction while the calibration complexity is confined to a one-time setup procedure rather than affecting ongoing measurements.
Data Source
AI summary
A method for measuring the noise factor (FDUT) of a device under test, which requires exclusively a network analyzer. The noise factor (FDUT) is calculated from the internal noise (NNWA) of the network analyzer determined in a calibration process, the power amplification (GDUT) of the device under test determined by measuring the S-parameters of the device under test, and the measured value (PNOISE) of the noise output (NNWA) applied at a first gate of the device under test without exciting the device under test with a noise signal.