Comparator Path Loss Compensation for Accurate DUT Signal Timing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Automated test systems face challenges in accurately measuring response signals from devices under test due to signal corruption caused by non-ideal electrical behavior in the signal path, leading to timing errors and false test results.
Innovation Solution
Incorporating a loss compensation circuit with a filter that generates a correction signal based on measured scattering parameters to compensate for signal losses, which is combined with the input signal to provide a corrected output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional comparator circuit is used to measure response signals from a DUT, then the system is simpler and less expensive, but signal corruption occurs due to non-ideal electrical behavior in the signal path leading to timing errors and false test results
Solution Approach 1:
The comparator circuit is segmented into multiple functional blocks: a first differential pair circuit for generating intermediate output signals, a second differential pair circuit for generating correction signals, and a summing circuit for combining these signals. This segmentation allows each block to perform a specific function in the signal correction process, improving measurement precision by addressing signal corruption systematically while keeping each individual block relatively simple.
Solution Approach 2:
An intermediary correction signal is introduced through the second differential pair circuit. This correction signal is generated based on the inverting input signal and used to compensate for signal corruption in the forward path. The summing circuit acts as a mediator to combine the intermediate output signal with the correction signal, effectively canceling out the effects of non-ideal electrical behavior without requiring complete redesign of the entire comparator system.
2Measurement precision
If signal path corrections are implemented to compensate for non-ideal electrical behavior, then measurement accuracy improves, but the circuit complexity increases due to additional compensation components
Solution Approach 1:
The correction signal path and the main signal path are merged at the summing circuit. The summing circuit combines the intermediate output signal from the first differential pair with the correction signal from the second differential pair, effectively merging the correction function into the existing comparator architecture. This approach improves timing accuracy by compensating for signal path distortions while avoiding the need for completely separate correction systems.
Solution Approach 2:
The circuit dynamically adjusts signal parameters through the differential pair circuits. The transconductance of the differential pairs is modulated based on the input signals, allowing the circuit to adaptively compensate for varying signal path conditions. This parameter change approach enables timing accuracy improvement without requiring fixed, complex correction networks for every possible signal condition.
Data Source
Figure 1~2
Figure 3
Figure 4
AI summary
A test system receives a test signal from a device under test (DUT) via a first signal path. A comparator circuit receives the test signal and, in response, generates an intermediate output signal based on a magnitude relationship between the test signal a comparator reference signal. A compensation circuit generates a correction signal that is complementary to a portion of the received test signal, such as to correct for loading effects of the first signal path. The test system further includes an output circuit configured to provide a corrected differential output signal that is based on a combination of the intermediate output signal and the correction signal.