Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

MOSFET (Si/SiC) Forum Discussions

User17810
Level 1
First question asked
Level 1
Hi, I have a question, is there any information on measurement techniques of high-speed voltage and current waveforms?
0 Likes
1 Solution
å__å__
Moderator
Moderator First like received Welcome! First question asked
Moderator
Tektronix, Lecory have released the voltage probes focus on the SiC component ,you can check it in their webpage.
For the current testing , the shunt resistor can be used here or detect the current directly by the Rogowski Coil from PEM http://www.pemuk.com/

View solution in original post

0 Likes
5 Replies
å__å__
Moderator
Moderator First like received Welcome! First question asked
Moderator
Tektronix, Lecory have released the voltage probes focus on the SiC component ,you can check it in their webpage.
For the current testing , the shunt resistor can be used here or detect the current directly by the Rogowski Coil from PEM http://www.pemuk.com/
0 Likes
User17669
Level 1
5 questions asked First question asked First reply posted
Level 1
Many thanks for the Infos so far, I have a further topic as I need to perform a non-inductive drain current measurement. How can this be done?
0 Likes
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
There is no simple answer to this question. The optimum solution depends on the current range and if you are considering a dedicated device characterization board or a measurement within an existing application.

Within an existing application usually the only current measurement that can be introduced without significant change of the structure is a Rogowski coil. This does not add inductance, but suffers from delay, limited bandwidth and
dV/dt induced disturbance.


In a dedicated characterization setup for low currents a coaxial shunt can be an attractive solution. Here you have to distinguish between internal series inductance (relevant for the bandwidth) and insertion inductance (limiting the di/dt you can achieve in the setup). So later one is dependent on how you integrate the shunt into your setup and it is rarely specified in the datasheet.


A characterization setup for higher current devices would most probably use pulse current transformers if you intend to use an off the shelf solution. Insertion inductance ins mainly governed by the way how you integrate the sensor into your setup, bandwidth by the number of windings, hence the transfer ratio) There are many publications on more advanced measurement methods, but then you would have to spend a lot of work on manufacturing and calibrating the sensor yourself.
0 Likes
User18949
Level 1
Level 1
electricuwe wrote:
There is no simple answer to this question. The optimum solution depends on the current range and if you are considering a dedicated device characterization board or a measurement within an existing application.

Within an existing application usually the only current measurement that can be introduced without significant change of the structure is a Rogowski coil. This does not add inductance, but suffers from delay, limited bandwidth and
dV/dt induced disturbance.


In a dedicated characterization setup for low currents a coaxial shunt can be an attractive solution. Here you have to distinguish between internal series inductance (relevant for the bandwidth) and insertion inductance (limiting the di/dt you can achieve in the setup). So later one is dependent on how you integrate the shunt into your setup and it is rarely specified in the datasheet.


A characterization setup for higher current devices would most probably use pulse current transformers if you intend to use an off the shelf solution. Insertion inductance ins mainly governed by the way how you integrate the sensor into your setup, bandwidth by the number of windings, hence the transfer ratio) There are many publications on more advanced measurement methods, but then you would have to spend a lot of work on manufacturing and calibrating the sensor yourself.


What kind of differential probes would you recommend/ do you use for measuring high side MOSFET gate and drain-source waveform?
0 Likes
electricuwe
Moderator
Moderator 5 sign-ins 25 replies posted 10 solutions authored
Moderator
We have used Bumblebee probes from PMK and IsoVu from Tektronix for measurement of highside gate signals. Highside drain source voltage measurement is less critical in regard to CMRR and could be done also with other non-optical differential probes.
0 Likes