Hi all,
this is my first post in this forum and I thank you in advance for any advice you could provide.

I am not an expert in electronics, but I need to design a very simple circuit to switch a 3.3V signal on a 50 ohm load that absorbs approx. 60 mA.

The switching should be able to operate at 1 MHz with a 5V square wave on the gate.

I prepared two very simple schematics. One uses a p-channel MOSFET and the other one an n-channel MOSFET (figure attached). I used the devices BSS138 and LP0701, which should in theory provide the right performance.

Looking in the internet, I see that p-channel MOSFETs are used in most cases when the load is connected to ground.

However, I simulated the two schematics in LTSpice and they provide similar performance (dispite the fact that the output signals are complementary since the two mosfets are open or close with 5V on the gate.

Could you please tell me why the p-channel solution should be preferred?

Thanks a lot

 

if this is a logic signal, have you considered the 50 ohm logic driver chips,
This is one of many with the nuumber "125" in them that will do nicely

https://www.ti.com/lit/gpn/sn74lvc1g125

 

if this is a logic signal, have you considered the 50 ohm logic driver chips,
This is one of many with the nuumber "125" in them that will do nicely

https://www.ti.com/lit/gpn/sn74lvc1g125

Thanks for the suggestion. I checked the specs of 50 ohm logic drivers, but they all seem to have lower output currents, in the order of 16 or 32 mA.
My load takes at least 66 mA, so I need something a bit more powerful. That's the reason why I was looking to logic level mosfets.

 

canI suggest you hunt a bit more,

e.g.
https://www.digikey.co.uk/product-detail/en/texas-instruments/SN74LVTH125DR/296-1708-1-ND/405002

there are 4 drivers in a package, drivers in a package can be paralleled , provide they are being drive the same,

There are many many digital drivers out there...