ATE Signal Splitting for Sub-Noise-Floor DUT Measurement
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Solution Overview
Problem
Automatic test equipment (ATE) struggles to accurately measure noise characteristics of devices under test (DUTs) when the ATE's noise floor is higher than the DUT's noise performance, leading to interference and inaccurate measurements.
Innovation Solution
The ATE splits the stimulus signal into two channels, each adding a different noise floor to the signal, and uses processing logic to estimate the deterministic and total power of the DUT signal through cross-correlation, allowing for the calculation of a lower noise floor and accurate signal-to-noise ratio (SNR) measurement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the ATE uses its standard measurement channel to measure the DUT signal, then the measurement process is simple, but the ATE noise floor interferes with accurate measurement of low-level DUT noise
Solution Approach 1:
The patent divides the measurement process into two separate channels: a first measurement channel that receives the DUT signal and a second measurement channel that receives only the ATE noise floor signal. This segmentation allows independent measurement of the DUT signal and ATE noise, which are then combined to achieve accurate noise characterization below the ATE noise floor.
Solution Approach 2:
The patent introduces a second measurement channel as an intermediary that specifically measures the ATE noise floor contribution. This intermediary channel enables the system to separate and quantify the ATE noise component, which is then subtracted from the total measurement to reveal the true DUT noise characteristics.
2Reliability
If the ATE noise floor is above the DUT noise performance level, then the ATE can operate with standard sensitivity, but the ATE cannot accurately measure noise characteristics below its noise floor
Solution Approach 1:
The patent employs periodic switching between measuring the DUT signal and measuring the ATE noise floor signal through the two channels. By periodically alternating measurements and using statistical processing, the system can extract accurate noise characteristics even when the ATE noise floor exceeds the DUT noise level.
Solution Approach 2:
The patent creates a copy of the measurement setup with two parallel channels, where one channel measures the DUT signal and the other measures the ATE noise floor. This copying approach allows the system to obtain a pure measurement of the ATE noise contribution without the DUT signal present, enabling accurate subtraction and recovery of sub-noise-floor DUT noise characteristics.
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 method enables accurate measurement of DUT noise characteristics below the ATE's noise floor by attenuating uncorrelated noise, improving the SNR calculation and reducing the noise floor, thus enhancing the measurement accuracy of DUTs with lower noise levels.
Implementation Method 1
The processing logic may comprise circuitry for estimating the second total power based on cross-correlation of the first channel signal and the second channel signal
Implementation Method 2
The processing logic may comprise circuitry for estimating the first power, and the circuitry may comprise a first single bin discrete Fourier transform (DFT) block corresponding to the first channel for generating a first set of coefficients of the first channel signal
Data Source
AI summary
Automatic test equipment (ATE) includes: a circuit to split a stimulus signal, which contains both deterministic and random (noise floor) spectra contents, from a device under test (DUT) into a first signal and a second signal; a first channel to receive the first signal, where the first channel adds a first noise floor to the first signal to produce a first channel signal; a second channel to receive the second signal, where the second channel adds a second noise floor to the second signal to produce a second channel signal, the first noise floor, the second noise floor and the DUT noise floor all being mutually uncorrelated; and processing logic to: estimate a first power of the deterministic stimulus signal, and estimate a second total power based on the first channel signal and the second channel signal.