120V 25A H-bridge circuit PCB

Thread Starter


Joined Apr 28, 2021
Hello, I am getting ready to do a pcb layout for the h-bridge configuration below which will serve to drive a brushed dc motor. This circuit is for my senior design and i would like to implement best practices to have a fully working circuit. My plan was to have a 4 layer board with a power plane at the top and a ground plane at the bottom and just connect all my low voltage traces in the 2nd and 3rd layer. I have been thinking about adding a bulk capacitor, but i am not sure if that would be necessary. I would appreciate any input, thanks.



Joined Oct 7, 2019
Why are you not using a H-bridge Gate driver that drives two MOSFETs at a time?
I think an op-amp is not right to drive the bottom MOSFETs.
If the timing is hard, there are Gate Drivers with built in dead time.

I cannot talk about PCB design without knowing what the voltages and currents are.
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Joined Feb 24, 2006
What provision have you made for deadtime in the switching signals? The last thing you want to happen is to have a short across the power supply.

I second @ronsimpson on using an opamp to drive a MOSFET gate. Definitely a suboptimal way to go.


Joined Nov 6, 2012
100ma is stout for an Op-Amp,
but it's not adequate to switch ~4nf of Gate Capacitance at high speeds.

BTW, a IXFH50N17 doesn't seem to exist, the closest thing seems to be a IXFH50N20,
and your Schematic does not include Voltages,
that Op-Amp drops at least 2-Volts off of the Supply, so keep that in mind.

What are You planning to use for Heat-Sinks ?
Where is the Power-Supply ?, that's one of the most important parts of the Circuit.