Actual test case: 1200V GaN HEMT power device dynamic characteristics test

In the future, high-voltage GaN devices will have greater development space in the industrial and energy application markets.

氮化镓器件是第三代半导体中的典型代表，具有极快的开关速度，能够显著提升功率变换器的性能，受到电源工程师的青睐。同时，极快的开关速度又对其动态特性的测试提出了更高的要求，稍有不慎就会得到错误结果。

Traditional GaN devices are mostly used in the consumer electronics market. The development of high-voltage GaN devices will help open up new application markets in the power electronics, new energy and electric vehicle industries. GaNPower is the world's first manufacturer to launch 1200V high-voltage silicon-based GaN power devices. The 1200V TO-252 packaged GaN device GPIHV15DK tested this time is of landmark significance in the market. The highest voltage of traditional GaN power devices generally remains in low-voltage applications.

In order to accurately test the dynamic characteristics of GaN HEMT power devices, the corresponding test system often needs to pay attention to the following points:

1. The measurement equipment has sufficient bandwidth to ensure that the switching process is not filtered

To meet this requirement, Tektronix's power device dynamic characteristics test system DPT1000A is equipped with the industry-leading oscilloscope MSO5 (1GHz bandwidth), optical isolation probe TIVP1 (1GHz bandwidth), high-voltage passive probe TPP0850 (800MHz bandwidth), Shunt (500MHz bandwidth)

2. Achieve the minimum loop connection between the probe and the measurement point to reduce the parasitic parameters introduced into the measurement loop and avoid non-existent oscillations or other abnormal waveforms in the measurement results.

3. Control the inductance of the power circuit and drive circuit in the test board to avoid severe oscillation of the switching waveform or exceeding the safe operating range of the device

For requirements 2 and 3, Tektronix provides a dedicated test board for GaN HEMT power devices to ensure the test effect. It has the following features:

a. The components are compactly laid out, the drive circuit is close to the device, and the inductance of the power circuit and the drive circuit are minimized

b. For devices of different packaging types, two forms of welding and crimping are provided, which can not only avoid the excessive parasitic voltage introduced by traditional sockets, but also ensure that the devices are firm and reliable.

c. A dedicated test socket is used when connecting the optical isolation probe TIVP1 and the high-voltage passive probe TPP0850 to the PCB, which minimizes the inductance introduced into the measurement loop while ensuring the repeatability of the measurement.

Taking the TO-252 test board as an example, we can see the various functional modules on it.

• Bottom tube device: Liangxinwei's 1200V GaN device GPIHV15DK

• Upper tube device: 1200V silicon carbide diode in TO-252 package

• Test points: gate signal test point, main loop current test point, source and drain Vds voltage test point

The Tektronix DPT1000A power device dynamic characteristics test system integrates the MSO58B high-resolution multi-channel oscilloscope, optical isolation probe, and dual-channel arbitrary waveform generator to achieve:

- Customized system design & automated testing software

- High bandwidth/high resolution test equipment to accurately characterize power devices under high-speed switching conditions

- Covers different types of chips such as high voltage, medium voltage, low voltage, pmos, GaN, etc., and different package chip tests

- Can provide single pulse, double pulse, reverse recovery, Qg, short circuit test and other test functions

Entering 1200V means that gallium nitride devices will play an important role in 800V electric drive or other high-voltage applications. At the same time, compared with silicon carbide devices, they will have greater cost advantages, proving that high-voltage gallium nitride devices will have greater development space in the industrial and energy application markets in the future.