Half-Bridge Circuit for Dynamic On-Resistance and Vth Instability
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Solution Overview
Problem
Existing measurement circuits for GaN-based power devices are unable to efficiently measure both dynamic on-resistance (Rds,on) and threshold voltage (Vth) instability due to limitations in pulse width, cost, and the need for separate circuits, which introduce variability in stress conditions and circuit parameters.
Innovation Solution
A novel evaluation circuit using a half-bridge configuration with an RL load and a switch combining circuit, allowing for simultaneous measurement of dynamic on-resistance and threshold voltage instability with shorter pulse widths and reduced cost, suitable for Group III-N based devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If separate test circuits are used to measure Vth instability and Rds,on instability, then each parameter can be measured independently, but circuit complexity increases and stress conditions become inconsistent
Solution Approach 1:
The patent combines Vth instability measurement and Rds,on instability measurement into a single integrated test circuit. The half-bridge circuit incorporates both measurement capabilities, allowing simultaneous evaluation of both parameters under identical stress conditions, thereby reducing circuit complexity while maintaining measurement accuracy
Solution Approach 2:
The test circuit is designed with multi-functionality to perform both Vth instability measurement and Rds,on instability measurement using the same circuit configuration. This universal approach eliminates the need for separate dedicated circuits for each measurement, reducing overall system complexity
2Measurement precision
If conventional curve tracer is used to measure Vth instability, then measurement can be performed, but pulse width is limited to hundreds of microseconds which is too large for actual switching frequency
Solution Approach 1:
The patent changes the measurement parameters by implementing a half-bridge circuit configuration that enables measurement of Vth instability with pulse widths reduced to microseconds range. This parameter change allows the measurement to reflect actual high-frequency switching conditions rather than the hundreds of microseconds required by conventional curve tracers
3Duration of action of moving object
If N1265A curve tracer is used to reduce minimum pulse width to 20 μs, then measurement speed improves, but the setup becomes too expensive to afford
Solution Approach 1:
The patent employs a cost-effective measurement approach using standard half-bridge circuit components and conventional measurement equipment instead of expensive specialized curve tracers. The solution achieves microsecond-range pulse width measurement capability through clever circuit design rather than relying on costly proprietary equipment
4Measurement precision
If test circuit with half-bridge and capacitor is used to measure Vth instability, then measurement is enabled, but it can only measure single switching cycle and does not discuss Rds,on instability
Solution Approach 1:
The patent designs a universal test circuit based on half-bridge configuration that can simultaneously measure both Vth instability and Rds,on instability. The circuit incorporates multiple measurement paths and signal processing capabilities that enable evaluation of both parameters across multiple switching cycles, enhancing the adaptability and versatility of the measurement system
Data Source
AI summary
A dynamic on-resistance and threshold voltage instability evaluation circuit for power devices and its operation method thereof are provided. The evaluation circuit includes a first switch element and a device under test which forms a half bridge circuit, an RL load, as well as a second switch element in parallel with a capacitor. The device under test is connected as a lower switch of the half bridge circuit. And the RL load enables repetitive hard switching operation of the device under test for dynamic on-resistance measurement. The second switch element in parallel with the capacitor enables threshold voltage measurement of the device under test. By adopting the circuit to characterize both instabilities of dynamic on-resistance and gate threshold voltage, the present invention is beneficial to achieving in shorter pulse width, faster measuring speed and inexpensive measuring equipment, and can thus be widely applied to group III-N based power devices.