Industry trends

Source Measure Unit (SMU) integrates digital multimeter, voltage source, current source, electronic load, pulse generator, waveform generator and other functions, and is widely used in power semiconductor testing, optoelectronic device research, transistor verification, etc. Application can simplify the test system and improve test efficiency.

Don't know how to choose an SMU? Let's find out

1. Confirm the maximum current and voltage range of the DUT to be tested

When selecting a source measure meter, it is necessary to first confirm the maximum current and voltage range of the DUT to be tested, and use this as a reference to select the output range of the source. This output range refers to the functional range of the source measure unit to output constant voltage/current. It should be noted here that due to the limitation of the total power of the source measure meter, its output cannot reach the maximum value of current output and voltage output at the same time.

The source measure meter adopts four-quadrant working mode. When the voltage and current are both positive, the source measure unit works in the first quadrant; when the voltage is negative and the current is positive, the source measure unit works in the second quadrant; when the voltage and current are both negative, the source measure meter works in the third quadrant. Quadrant; when the voltage is positive and the current is negative, the source measure meter works in the fourth quadrant.

2. Avoid the influence of device self-heating effect on test results

The third-generation semiconductor materials represented by SiC and GaN have the characteristics of high band gap, high thermal conductivity, high breakdown field strength, and high electron saturation drift rate. Status matters. Pulse characterization is an effective solution to the self-heating effect. Its principle is to reduce the influence of temperature rise on semiconductor performance by short-time energization (pulse), so as to obtain more realistic data and achieve faster and more accurate measurements.

For the application scenarios of high-speed digitization or waveform acquisition, the pulse test has higher resolution, can achieve better sampling performance, and can obtain more accurate transient characteristics under the same bandwidth, which is the ideal choice for waveform capture and transient characteristics applications. 

3. Focus on comprehensive test indicators

When considering test specifications for a Source measure unit, key terms should not be overlooked, such as: accuracy, repeatability, resolution, sensitivity, and NPLC sampling time.

Taking accuracy as an example, the measurement accuracy of the source measure meter should include current measurement accuracy and voltage measurement accuracy. For example, in the static parameter test of power devices, it is particularly important to pay attention to the output and measurement accuracy under the high current range of 1000A and above.

4. Confirm the number of channels required

When the user has multiple testing needs, we recommend the user to choose the PRECISE CS series plug-in digital source measure meter, which can realize simultaneous measurement and output of up to 40 channels.

You can also choose to connect multiple single-channel SMUs together, which can be used as a multi-channel source/measure unit without complicated wiring. Through this function, you only need to set the relevant trigger settings for the master and slave, the master can send test data from A to the slave, and after connecting the dedicated trigger signal line, the synchronization between multiple source measure units can be realized.