Dynamic Compensation Circuit for DC Offset Errors
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Solution Overview
Problem
Existing test and measurement systems require manual removal and recalibration of accessories, such as probes, which can be impractical and lead to measurement errors due to environmental and mechanical stress affecting optical sensors, especially when measuring DC signals.
Innovation Solution
A test and measurement system with a compensation unit integrated into the accessory that dynamically applies compensation signals in real-time, allowing for continuous calibration without removing the accessory from the device under test, using a controller to compare input and output signals and adjust for DC/LF offset errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If optical sensors are used to measure DC signals, then measurement capability is extended to DC/LF range, but measurement precision deteriorates due to DC/LF offset shifts caused by temperature and mechanical stress
Solution Approach 1:
The patent implements a feedback mechanism where the accessory sends its output signal back to the host, which compares it with the original input signal. The host then sends compensation signals back to the accessory to correct DC/LF offset shifts. This continuous feedback loop maintains measurement precision while preserving the extended DC measurement capability of optical sensors.
Solution Approach 2:
The patent dynamically changes the compensation signal parameters (amplitude, frequency) based on the detected offset shifts. By adjusting these parameters in real-time, the system compensates for environmental effects on optical sensors, maintaining measurement precision across the full DC to high-frequency range.
2Ease of manufacture
If manual compensation is performed by removing the accessory and connecting it to a calibration stimulus, then compensation can be performed with simple equipment, but productivity deteriorates due to removal and reattachment operations
Solution Approach 1:
The system performs self-compensation by using the accessory's own output signal as the reference for comparison. The accessory sends its output back to the host, which automatically generates and applies compensation signals without requiring external calibration equipment or manual intervention. This eliminates removal/attachment operations while maintaining compensation capability.
Solution Approach 2:
The patent merges the compensation function with the measurement function by integrating the compensation unit within the accessory itself and using the same signal path for both measurement and compensation. This combination eliminates the need for separate calibration equipment and manual operations, improving productivity while maintaining compensation effectiveness.
3Measurement precision
If the accessory is removed from the DUT for compensation, then accurate compensation can be performed, but ease of operation deteriorates due to manual removal and reattachment
Solution Approach 1:
The feedback mechanism allows the accessory to be compensated while remaining connected to the DUT. The output signal is fed back to the host for comparison and compensation signal generation, enabling accurate compensation without physical removal. This maintains both compensation accuracy and ease of operation.
Solution Approach 2:
The system performs preliminary compensation by continuously monitoring the output signal and applying compensation signals before measurement errors accumulate. This preliminary action ensures accurate compensation while the accessory remains in its operational position, eliminating the need for removal and reattachment.
Data Source
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AI summary
A test and measurement system including a device under test, an accessory, a controller and a test and measurement instrument. The accessory is connected to the device under test and includes a signal input to receive an input signal from the device under test, a compensation unit configured to apply a compensation signal internal to the accessory, and a signal output to output an output signal read from the device under test. The controller is connected to the accessory and includes one or more receivers to receive the input signal and the output signal from the accessory, and a microcontroller or correction circuit configured to compare the input signal and the output signal and in response to the comparison provide a compensation signal to the compensation unit.