Hi,
I apologize if my question is stupid, but I don't have the knowledge to answer it...
A friend of mine asks me if it is possible to measure the MOSFETs in order to get them matched, like we use to do with the Bipolar transistors. And of course, HOW to proceed...
The MOSFETs that he would like to get matched are the IRFP140N.
Thank you very much for your reply,
I apologize if my question is stupid, but I don't have the knowledge to answer it...
A friend of mine asks me if it is possible to measure the MOSFETs in order to get them matched, like we use to do with the Bipolar transistors. And of course, HOW to proceed...
The MOSFETs that he would like to get matched are the IRFP140N.
Thank you very much for your reply,
Much has been said, do a search.
Here's a simple setup I use for static test: connect an amp meter to Id, a volt meter to Vgs, turn U1 to your target drain current (Id), and read the volts required (Vgs).
The MOSFet may need a heatsink, and you may need to wait until thermal equilibrium is reached.
Edit
The pic shows a NMOSFet. Reverse polarity for PMOS.
Here's a simple setup I use for static test: connect an amp meter to Id, a volt meter to Vgs, turn U1 to your target drain current (Id), and read the volts required (Vgs).
The MOSFet may need a heatsink, and you may need to wait until thermal equilibrium is reached.
Edit
The pic shows a NMOSFet. Reverse polarity for PMOS.
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If you only need a few, it's best to just buy matched pairs. You'd need to buy a lot of parts
to get just a few close matches. Someone here may have a few matched pairs to sell.
to get just a few close matches. Someone here may have a few matched pairs to sell.
You could connect the gate to the drain, connect a current meter in series, put two of those circuits in parallel and force a current through the whole thing. If the two meters show nearly the same current (half the total current), they are well matched.
Using this method, when the total current is relatively small, you mainly check threshold voltage matching, when it is large (don't forget to cool the MOSFETs then), mainly beta matching.
Using this method, when the total current is relatively small, you mainly check threshold voltage matching, when it is large (don't forget to cool the MOSFETs then), mainly beta matching.
@Zung:
Thank you very much for your detailed explanation and the schematiks !
I believe I should build a PCB with 3 appropriate connectors, in order to simplify the measurement of the Mosfets (and switch from a mosfet to another)...
I have not found something similar, but maybe I have performed a good search?
@rayma:
There are 8 Mosfets per channel for a non-symetric amp (using RCA) and 16 for a symetric amp (using XLR): so I believe there are too many, and anyway in case the prototype becomes commercial, there is a need for autonomy...
@MarcelvdG:
your explanation is not clear for me, but we should sort it out with the Zung schematics.. thank you anyway!
Have a nice weekend
Thank you very much for your detailed explanation and the schematiks !
I believe I should build a PCB with 3 appropriate connectors, in order to simplify the measurement of the Mosfets (and switch from a mosfet to another)...
I have not found something similar, but maybe I have performed a good search?
@rayma:
There are 8 Mosfets per channel for a non-symetric amp (using RCA) and 16 for a symetric amp (using XLR): so I believe there are too many, and anyway in case the prototype becomes commercial, there is a need for autonomy...
@MarcelvdG:
your explanation is not clear for me, but we should sort it out with the Zung schematics.. thank you anyway!
Have a nice weekend