Ultra-Fast Current Shunts UFCS
■ Market-leading >1GHz Bandwidth
■ Ultra-low <200 pH Insertion Inductance
■ Various sizes available: 1mΩ, 5mΩ, 11mΩ, 24mΩ, 52mΩ
■ For WBG switching loss and pulse current measurements
Using the UFCS for Accurate Current Measurements
Our Ultra-Fast Current Shunts (UFCS) are compact, high-performance probes designed for precise current measurements. Invented and designed for power electronics experts, our UFCS deliver unparalleled accuracy when connected to an oscilloscope, either directly or via a voltage probe such as our FireFly® optical probe head.
What is the purpose of the UFCS's design, and how do I connect it?
The UFCS is designed to ensure high-quality signal retrieval and precise current measurements. It features:
- A female SMA connector at the top of the shunt body for signal output.
- A protruding plate element with conductive surfaces on the front and back at the bottom of the shunt.
You'll find the following markings on the shunt body:
- "SHLD" on the front conductive surface (shield connection).
- "IN" on the back conductive surface (input connection).
These markings indicate the correct connections:
- The "IN" (input) surface should be connected to your current source.
- The "SHLD" (shield) surface should be connected to the return path of your current loop. This is typically ground, your shield, or the current output.
This setup ensures that all current passes through the shunt, allowing for accurate measurements.
What does “SHLD” mean, and why is it not labeled “GND”?
The “SHLD” (shield) marking is used to indicate the other leg of your current loop, not necessarily ground. Internally, the shield connection is tied to the shield of the oscilloscope to prevent accidental damage from high voltages.
- If you are connecting directly to an oscilloscope, spectrum analyzer, or similar instrument, SHLD must be connected to the same potential as the oscilloscope ground, just like with a passive probe.
- If you are using an optical probe head such as the optical probe head FireFly, you have more flexibility and can place the UFCS anywhere in the circuit.
Do I need to use a 50 Ohm termination with the UFCS?
Yes, the UFCS requires a 50 Ohm termination for proper operation.
- If you're connecting directly to an oscilloscope, make sure your scope is set to 50 Ohm input mode, or use an external 50 Ohm terminator.
- Some probes have a 1V input range, which works with the UFCS. However, oscilloscopes typically have a 5V range, so ensure proper termination for compatibility.
Establishing a connection does not require full contact across the entire conductive surface. A reliable and safe electrical connection—such as using a soldered wire—is fully sufficient for optimal performance.
Can I use the UFCS directly with an oscilloscope or other measurement systems?
Yes, the UFCS is compatible with any device that has a 50 Ohm input. It has been tested with a variety of setups, including Oscilloscopes, Spectrum Analyzers, and many more.
Some older measurement instruments might lack a 50 Ohm input option and might be incompatible. However, newer models may now include this capability—check your instrument specifications.
Note that SHLD needs to be connected to the same voltage as your oscilloscope ground. Just like when you use a passive probe.
We highly recommend the FireFly® for isolated measurements, and our High-Speed Differential Probe HSDP.
How does the UFCS shunt improve reliability and safety?
The UFCS's design ensures that all current passes through the shunt for accurate measurement, while its shield connection minimizes the risk of damage to your equipment. This simple yet effective configuration delivers reliable and precise current measurements with ease.
What are some of the typical UFCS shunt applications?
The solder-in PMK UFCS, with their compact size and high current-handling capabilities, are specifically designed for demanding tasks such as:
- WBG (Wide-Bandgap) switching loss measurements
- Pulse current analysis
These shunts excel in analyzing pulsed current signals with high-frequency components in precise detail, thanks to their industry-leading features:
- >1 GHz bandwidth for detailed signal analysis
- Ultra-low insertion inductance (<200 pH) for highest signal fidelity
Whether you’re measuring switching losses or investigating high-speed transients, the UFCS ensures accurate and reliable results, even in the most challenging environments.
Are the UFCS shunts typically soldered onto the PCB?
While the shunt can be soldered onto the PCB, it is not strictly necessary. It can also be clamped between conductive surfaces or connected by soldering a cable to both the SHLD and IN conductive surfaces. The key requirement is that the shunt remains an integral part of the circuit, ensuring that all current flows through it. A full-surface connection between the SHLD and IN surfaces is not required.
How can I connect the UFCS shunt to a FireFly® MMCX tip?
We recommend using a 1V FireFly® tip FF-MMCX-1V (MMCX type) for optimal signal attenuation, see table below.
Connecting our UFCS shunts to the FF-MMCX-1V tip requires an SMA plug (male) to MMCX jack (female) adapter, see table below. Other high-quality adapters, e.g. the Wurth 64403260111000, or equivalent adapters from Pasternak, Amphenol, etc, will work, too.
Learn more about our optically isolated FireFly® probe here.
| Order number | Article | |||
|---|---|---|---|---|
|
$863.00 USD
|
|
FF-MMCX-1V | FireFly®, probe tip cable, MMCX | |
|
$30.00 USD
|
|
018-291-970 | SMA plug (male) to MMCX jack (female) adapter. 50Ω. | |
Example 3D Render
For illustration purposes. Please download 3D file for model data.
1mΩ Ultra-Fast Current Shunt Models
Bandwidth still to be determined.
| Article number | Output | Resistance | Bandwidth (3dB) | Insertion inductance | Info | |||
|---|---|---|---|---|---|---|---|---|
|
$454.00 USD
|
|
UFCS-R001 | SMA (F) | 1 mΩ | >600 MHz | 120 pH | Single pack | |
|
UFCS-R001x10 | SMA (F) | 1 mΩ | >600 MHz | 120 pH | Pack of 10 | ||
|
UFCS-R001x25 | SMA (F) | 1 mΩ | >600 MHz | 120 pH | Pack of 25 | ||
5mΩ Ultra-Fast Current Shunt Models
| Article number | Output | Resistance | Bandwidth (3dB) | Insertion inductance | Info | |||
|---|---|---|---|---|---|---|---|---|
|
UFCS-R005 | SMA (F) | 5 mΩ | >900 MHz | 140 pH | Single pack | ||
|
UFCS-R005x10 | SMA (F) | 5 mΩ | >900 MHz | 140 pH | Pack of 10 | ||
|
UFCS-R005x25 | SMA (F) | 5 mΩ | >900 MHz | 140 pH | Pack of 25 | ||
11mΩ Ultra-Fast Current Shunt Models
| Article number | Output | Resistance | Bandwidth (3dB) | Insertion inductance | Info | |||
|---|---|---|---|---|---|---|---|---|
|
$454.00 USD
|
|
UFCS-R011 | SMA (F) | 11 mΩ | >1GHz | 110 pH | Single pack | |
|
UFCS-R011x10 | SMA (F) | 11 mΩ | >1GHz | 110 pH | Pack of 10 | ||
|
UFCS-R011x25 | SMA (F) | 11 mΩ | >1 GHz | 110 pH | Pack of 25 | ||
24mΩ Ultra-Fast Current Shunt Models
| Article number | Output | Resistance | Bandwidth (3dB) | Insertion inductance | Info | |||
|---|---|---|---|---|---|---|---|---|
|
$454.00 USD
|
|
UFCS-R024 | SMA (F) | 24 mΩ | >1 GHz | 140 pH | Single pack | |
|
UFCS-R024x10 | SMA (F) | 24 mΩ | >1 GHz | 140 pH | Pack of 10 | ||
|
UFCS-R024x25 | SMA (F) | 24 mΩ | >1 GHz | 140 pH | Pack of 25 | ||
52mΩ Ultra-Fast Current Shunt Models
| Article number | Output | Resistance | Bandwidth (3dB) | Insertion inductance | Info | |||
|---|---|---|---|---|---|---|---|---|
|
$454.00 USD
|
|
UFCS-R052 | SMA (F) | 52 mΩ | >900 MHz | 150 pH | Single pack | |
|
UFCS-R052x10 | SMA (F) | 52 mΩ | >900 MHz | 150 pH | Pack of 10 | ||
|
UFCS-R052x25 | SMA (F) | 52 mΩ | >900 MHz | 150 pH | Pack of 25 | ||
ultra-fast current shunts
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