How to choose a probe for high voltage power accurate measurement? DP0001A pats you on the shoulder~
This article is about 4,000 words and introduces the following content
• Fundamentals of Oscilloscope Probes
• Third generation wide bandgap semiconductor testing
• DP0001A High Voltage Differential Probe
How to accurately measure the high voltage power of WBG power devices, power converters or motor drives?
The high-voltage differential probe DP0001A with high bandwidth and low loading effect pats you~
DP0001A Skills Library
Accurately measure 1kV transient pulses with edge speeds (10%-90%) as fast as 1.2ns in modern switching power supplies.
共模抑制比(CMRR)超过 90 dB，能够显著简化噪声较大的高共模功率电子环境所面临的测量难题。
When used with Infiniium oscilloscopes, it supports automatic switching of attenuation ratios.
When used with the N7013A extreme temperature extension kit, it can be used over the -40 °C to +85 °C temperature range.
01.
Fundamentals of Oscilloscope Probes
The oscilloscope probe is the connection between the oscilloscope and the device under test. The selection of the oscilloscope probe will directly affect the signal quality of the oscilloscope input. Most people pay more attention to the use of the oscilloscope itself, but tend to ignore the selection of the probe.
In fact, the probe is the middle link between the measured signal and the oscilloscope. If the signal is distorted at the probe, then no matter how good the oscilloscope is, it is useless. Therefore, before measuring the signal, the first thing you need to do is to choose a suitable probe.
How to choose an oscilloscope probe?
Generally, we will make a comprehensive selection based on the following six factors:
01. Signal bandwidth
The bandwidth of the entire measurement system is determined by the oscilloscope, probe, and signal source.
☛ For an oscilloscope and probe with a Gaussian frequency response, the system bandwidth is:
☛ For a flat-responding oscilloscope and probe, the system bandwidth is:
From the system bandwidth calculation formula, we can see that the probe has a great impact on the bandwidth of the measurement system. Therefore, for high-speed differential or single-ended detection in embedded design, it is necessary to select a suitable probe to match the oscilloscope for measurement when selecting the measurement system.
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With its extremely low input capacitance and flat response, the InfiniiMax 3.5 GHz 1131B differential probe is an ideal match for Infiniium 2.5 GHz to 3 GHz oscilloscopes.
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The InfiniiMax 5 GHz 1132B differential probe is an ideal match for the Infiniium 4 GHz oscilloscopes.
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The InfiniiMax 7 GHz 1134B differential probe is an ideal match for the Infiniium 6 GHz oscilloscopes.
02. Impedance of the object being measured
When we choose a probe, it is best to choose a probe with high impedance and low capacitance to minimize the probe load of the signal source. For general debugging and fault diagnosis of most analog or digital circuits such as general CMOS and TTL circuits, a high-impedance passive probe (such as Keysight N2873A, 500 MHz, 9.5 pF input capacitance) is sufficient.
However, in the high-frequency range, such as HSIC USB for fast, low-power connections between chips, ordinary high-impedance passive probes are not suitable.
Figure 1: USB test description
This is because, although typical LVCMOS inputs have low leakage current, they require high input capacitance. HSIC USB only allows 14 pF of total capacitive load including PC board traces and receiver capacitance. Therefore, HSIC testing requires lower capacitive load.
另外，HSIC使用相对较高的频率。STROBE的基本频率为240 MHz，至少需要1.5 GHz带宽才能清楚看到STROBE和DATA之间的时序关系。所以对这类高频测量应用来说，最好直接选用有源探头（例如Keysight N2795A /N2796A， 1/2GHz 带宽， 1 pF 输入电容），价格只需1000美元左右，相比市面上4pf的无源探头也不会贵很多，关键有源探头电容负载效应显著的降低，因而可以更精确地观察快速信号，特别适合于数字系统设计、元器件设计/表征及教育研究方面的应用。
03. Signal size or dynamic range
04. Single-ended or differential measurement
05. Output impedance of the probe
06. Price
Understand the basis for selecting oscilloscope probes!
What types of oscilloscope probes are available?
The DP0001A high-voltage differential probe adopts a special design. The common-mode withstand voltage does not change with the change of the attenuation ratio. At a low attenuation ratio, it still maintains a high bandwidth and common-mode withstand voltage, which is very suitable for the Vgs voltage test of the upper tube. In particular, it is used to test the Vgs voltage waveform of SiC and GaN wide bandgap power devices with high bandwidth requirements.
Figure 6: Common-mode withstand voltage of DP0001A high-voltage differential probe
In addition, when the DP0001A is used with an Infiniium oscilloscope, the probe supports automatic attenuation ratio switching, that is, the probe attenuation ratio is automatically set to a value that matches the test, so that the dynamic range of the probe is greater than or equal to the dynamic range required to measure the current input signal.
Finally, Keysight Technologies provides a complete series of probe products to meet various test needs. For details, please click the button to download in the PDF file below:
Figure 7: Keysight's complete probe product line
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Resources include the poster A Signal's Journey Inside an Oscilloscope, a complete line of Keysight oscilloscope probes.
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references:
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USB and HSIC Protocol Triggering and Decode
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Briefing on the Third Generation Semiconductor Industry Technology Innovation Strategic Alliance
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Switching Power Supply Design (3rd Edition), Pressman, Abraham I, Electronic Industry Press, 2010.
About Keysight Technologies
We are committed to helping enterprises, service providers and government customers accelerate innovation and create a secure and connected world. Since the founding of HP in 1939, Keysight Technologies has been operating independently as a new electronic test and measurement company on November 1, 2014. We continue to uphold the same entrepreneurial spirit and passion to start a new journey, inspire global innovators and help them achieve goals beyond imagination. Our solutions are designed to help customers innovate in 5G, automotive, IoT, network security and other fields.
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