Leakage-Compensated FET Switch for Precision High-Voltage Testing
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Solution Overview
Problem
Solid state switch devices, such as those using field-effect transistors (FETs), experience leakage currents due to non-idealities, which affect power efficiency and measurement accuracy in precision measurement apparatuses and high voltage automated test equipment.
Innovation Solution
A solid state switch device is designed with a compensation circuit that includes a sense device and a current amplifier. The sense device generates a leakage current correlated with the switch component's leakage current, and the current amplifier produces an estimated switch component leakage current to compensate for the original leakage, thereby reducing its impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a solid state switch device is used, then switching functionality is provided, but leakage current is generated which reduces power efficiency and measurement accuracy
Solution Approach 1:
The patent creates a scaled-down copy of the switch component called a 'sense device' that replicates the leakage current characteristics. This sense device is proportionally smaller but maintains the same leakage behavior pattern, allowing the leakage current to be measured and compensated without affecting the main switch's functionality.
Solution Approach 2:
The patent implements a feedback mechanism where the leakage current generated by the sense device is amplified and fed back to the switch component's drain terminal. This feedback loop continuously compensates for the leakage current, counteracting its harmful effects and maintaining measurement accuracy and power efficiency.
2Reliability
If a solid state switch device is used, then switching functionality is provided, but leakage current reduces measurement accuracy in precision measurement apparatuses
Solution Approach 1:
The sense device creates an accurate scaled copy of the switch component's leakage characteristics. By measuring the leakage current in this controlled sense device and amplifying it appropriately, the system can generate a compensation signal that precisely counteracts the leakage current affecting measurements, thereby maintaining high measurement accuracy.
Solution Approach 2:
The patent converts the harmful leakage current into a useful compensation signal. By intentionally generating a scaled version of the leakage current through the sense device and amplifying it, the system transforms the problematic leakage into a beneficial counter-signal that cancels out the original leakage, thereby improving measurement precision.
3Loss of energy
If a compensation circuit is added to reduce leakage current, then power efficiency is improved, but device complexity increases
Solution Approach 1:
Instead of implementing complex active compensation circuits that would require multiple components and control logic, the patent uses a simplified approach by creating a proportionally scaled sense device. This copy inherently replicates the leakage characteristics, and with a simple current amplifier, the compensation is achieved without significant increase in circuit complexity.
Solution Approach 2:
The sense device essentially serves itself by naturally generating the leakage current that needs to be compensated. The system uses the same physical phenomenon (leakage current) that is problematic in the main switch to create the compensation signal, eliminating the need for external control circuits or additional active components that would increase complexity.
Data Source
AI summary
A new field-effect transistor (FET) based switch for use in/with high voltage precision instruments is provided. The switch can enable leakage compensation. The switch can comprise a FET device and a compensation circuit coupled to the FET device to replicate and compensate for the FET device leakage, such that the switch appears not to leak current. The compensation circuit may comprise a sense device which acts as a scaled replica of the FET device being compensated. The sense device's leakage current can then be measured, reproduced at the scale factor, and injected back to the drain terminal of the FET device.