Get to market faster with your SiC and GaN based design

 
  • Are your GaN HEMTs and SiC MOSFETs blowing up?
  • Are faster switching speeds on your power devices causing ringing and shootthroughs that you cannot debug?
  • Are you having trouble optimizing gate drive performance and deadtime on your half-bridge circuits?
  • Are you having trouble making GaN HEMT or SiC MOSFET perform just right?
  • Are you having trouble getting the promised efficiency performance from your fast switching power converter?

The power electronics industry has relied on silicon-based MOSFETs and IGBTs for most of their power switching needs since the 1980s. Although these are well understood and reliable technologies, silicon technology is reaching its limits because of increasing efficiency and power density demands from industries such as automotive, data-centers, renewable systems, consumer electronics, and industrial power electronics.

After years of research and design, SiC (Silicon Carbide) and GaN (Gallium Nitride) power devices from companies such as Wolfspeed, EPC, GaN Systems, Rohm, Infineon, Semikron, Transphorm, and ST are becoming more viable. SiC, with its capability of driving high power at high voltages for high power applications, and GaN, with its super high-power density for medium to low power applications, are pushing the limits of what is possible with silicon-based designs in efficiency and power density.

SiC has found its place in applications like PV inverters and high performance motor drives for automotive power trains and locomotives. GaN is carving its niche in data-center power, wireless power, consumer power supplies, and automotive and military/government power electronics.

These devices, though high performance, come with challenges for designers. Setting cost and reliability aside, these power devices are not drop-in replacements for their silicon counterparts.

Some of the biggest challenges working with SiC and GaN devices are the gate drive requirements. SiC requires much higher gate voltage (Vgs) with a negative bias for turn off. GaN, on the other hand, has much lower threshold voltage (Vth), requiring tight gate drive designs. Wide band gap (WBG) devices, by the nature of their physics, also have a higher body diode voltage drop which requires much tighter control of dead-time and turn-on/turn-off transitions. To gain real benefits from these devices, they need to be switched quite fast which requires tight parasitic controls on the layout. These “power” designs are acting like “RF” designs, so due diligence is required to optimize these designs.

Solving these challenges is tough for engineers. More important is accurate visibility into all these signals so that the right design decisions can be made in a timely fashion. Increasing design margins and overdesigning will only drive costs up and bring performance down. Using the right measurement equipment then makes all the difference.

Reacting to the challenges faced by engineers working on these challenges, Tektronix is introducing the  SiC MOSFET and GaN FET Switching Power Converter Analysis Kit, the only solution in the market that accurately characterizes most critical parameters for optimizing power electronics topologies that use technology like SiC, GaN or any other fast switching silicon power devices.

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The kit provides everything required to accurately test gate drive timing, gate drive performance, Vgs, Vds, Id, and turn-on/turn-off on both high and low side power switches. Accurate characterization of high-side and low-side switches simultaneously also enables precise dead-time optimization to get the best performance out of these designs. Additionally, it comes with powerful 5PWR software which enables testing switching losses, conduction losses, magnetic losses, input and output power quality measurements, and overall power efficiency.

What’s in the kit?

  • 5Series MSO: 1GHz oscilloscope (4,6, or 8 Ch)
  • 5PWR Software: Advanced power analysis software
  • TIVH08: (2.5KV, 800MHz) High voltage isolated differential probes
  • TIVH05 (Optional): (2.5KV, 500MHz) High voltage isolated differential probes
  • TIVM1 (Optional): (50V, 1GHz) High BW isolated differential probes
  • TPP1000 (Free): (1GHz) High BW passive probe (standard with scope)
  • MMCX Tip for TPP1000 (Optional): Tip for high BW performance
  • GaN Half-bridge Demo Board Instruction Guide: Getting Started Guide using GaN Half-bridge demo board

FAQ:

Is this kit designed only for SiC or GaN based power designs? What about silicon-based MOSFETs and IGBTs?

  • This kit is designed for all power converters/inverters that use fast switching power devices. SiC and GaN technologies are generally the fastest switching power devices and will benefit most from this kit.

You mentioned “Fast Switching.” What does that mean? How do I know what bandwidth to pick?

  • Fast switching refers to the turn-on/turn-off transitions of a power device and not the switching frequencies of the design.
  • It’s important to know how fast your power switches are going to transition to determine the bandwidth you need on your test setup. Switching frequency is not a good measure for selecting bandwidth specifications on probes and scopes.
  • Most GaN devices in the market have turn-on/turn-off time below 10nS. These fast switching times can result in ringing and aberrations at 100Mhz or higher frequencies. If your converter switches at 100s of kHz, the probes and scopes you would need to design would far exceed 100MHz.

 How were all the parts in the kit chosen?

  1. 5 Series MSO Oscilloscope is a high resolution (12 bit) oscilloscope ideal for testing small voltages in presence of much higher voltages. For example, testing Vgs, RDS_ON, and conduction losses in presence of Vds voltage requires high vertical resolution. Additionally, it has 8 available channels for you to see more timing signals at the same time to optimize your performance.
  2. 5-PWR software is designed to run automated, accurate, and repeatable power measurements for calculating switching losses, conduction losses, RDS_ON, magnetic losses, SOA, and more under real operating conditions.
  3. GaN Half-bridge Demo Board Instruction Guide is a demo guide designed to remove guesswork from the setup to get accurate measurements with the kit.
  4. TIVH08 IsoVu is an 800MHz isolated differential voltage probe rated for 2.5KV differential voltage and 60KV common mode voltage, and for testing VDS and VGS signals on high voltage SiC and GaN power converters. This probe is ideal for testing fast dv/dt high voltage signals common to SiC and GaN power devices.
  5. TIVH05 IsoVu is a 500MHz isolated differential voltage probe rated for 2.5KV differential voltage and 60KV common mode voltage, and for testing VDS and VGS signals on high voltage SiC and GaN power converters. This probe is ideal for testing fast dv/dt high voltage signals, where 800MHz is not required.
  6. TIVM1 IsoVu is a 1MHz isolated differential probe for testing fast dv/dt on low voltage (<50 V) signals such as VGS and shunt voltage. TIVM1 is not ideal for VDS voltages due to lower voltage ratings and input impedance.
  7. TPP1000 is a 1GHz high bandwidth passive probe that comes as standard equipment with the MSO5 oscilloscope, with one probe per channel. This probe is ideal for testing ground referenced high dv/dt signals such as VGS_lo/VDS_lo and shunt voltages.
  8. MMCX shielded tip is a screw-in adapter for TPP1000 (1GHz) passive probe. It makes high frequency, ground referenced measurements more accurate by eliminating ground loops.

Do I need special test points on my board?

  • It depends on your design. If your operating voltages are lower than 300V and switching speeds require >500MHz bandwidth, you need shielded MMCX connectors. MMCX connectors are quite common in RF applications, and you need them to maintain the frequency response.
  • For relatively slower switching speeds, especially where your signal voltage is >50V, you can use square pin connectors or square pin adaptors with MMCX connectors.
  • Keep in mind that the Common Mode Rejection Ratio (CMRR) and frequency response degrades with square pin or any other adapters you use.
  • Regardless of which tip or adapter is used, good RF design practices should be followed to achieve the best performance. Always use the shortest lead length possible to minimize lead inductance and RF pick-up.
  • Refer to the product page to see examples of MMCX connectors and information on exact requirements.
  • Watch this video on creating unplanned test points with MMCX connectors.

Can I configure the kit?

  • Depending on your application and switching speeds, you can configure the kit for the appropriate bandwidth and number of measurement channels needed.

Is the kit expensive?

  • If you are working on fast switching power converter designs with either SiC MOSFETs, GaN FETs, or fast switching MOSFETs and IGBTS, this is the only solution in the market to test all switches, especially high-side ones, simultaneously, allowing you to optimize the dead-time, performance, and overall efficiency.
  • We have had numerous interactions with engineers who were struggling for months to solve ringing, shoot-throughs, and noise issues, due to high frequency common mode voltage. This kit allows you to solve those issues in days or hours, saving time and money spent in board revisions.

What if I already have some of the parts in the kit?

  • Use this kit as a laundry list and reach out to us for the parts you don’t have. We’ll be happy to help you out.

What other applications can I use this kit for?

  • MSO5 oscilloscope is one of the most versatile and user-friendly scopes in the market. It can be used for any other application that requires a scope with your selected bandwidth and specifications.
  • For IsoVu, it can be used for any differential probe application or even a power rail probe application to a certain degree.
  • This kit can also be used for the following applications with some modifications:
    • Double pulse testing (requires other products)
    • Bulk current injection
    • ESD testing
    • Differential voltage testing in EMI/EMC applications
    • Any differential measurement application within specifications

I have never used this equipment before. Can you help?

Are there upgrade options or expansion options?

  • The MSO5 scope is compatible with all modern Tektronix probes and can be upgraded and updated for other applications. See details on the MSO5 product page.
  • 5PWR software can be upgraded to add features on a later date.
  • For IsoVu, there are tips you can buy in addition to the standard tips, depending on your voltage requirements. See details here.

Are the pieces compatible with other Tek probes/scopes?

  • The MSO5 scope is compatible with all modern Tektronix probes. See details here.
  • IsoVu can be used with most modern Tektronix scopes. See details here.

What is my incentive in buying this kit versus individual parts?

  • The kit gives you everything you need for this application.
  • You will get all the instructions to get started and reduce your learning curve.
  • All parts are guaranteed to work together for this application.
  • It will make it easy for you to order all at once.

Where can I get more information?

Go to the solution webpage.

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