HFU HF Underground
Technical Topics => The RF Workbench => Topic started by: Charlie_Dont_Surf on December 18, 2020, 2214 UTC
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Texas Instruments has been introducing some nice integrated products composed a GaN transistor or transistors with integrated drive and protection circuitry (over current, over temperature, etc.)
These look pretty sweet for HF transmitter applications where size matters (we all know that size matters. :D ), though I have not yet tried to make one yet.
https://www.ti.com/power-management/gallium-nitride/products.html (https://www.ti.com/power-management/gallium-nitride/products.html)
Since they are integrated products in ~8 mm x ~8 mm QFN packages, you may have to pay more attention to power dissipation than you might with a TO-220 or TO-247. You may consider putting a heatsink on bottom side of the PCB. It will also force you to pay (yet) more attention to efficiency. On the other hand, if you aren't careful enough with the above, the integrated over temperature protection will notify you of that and save you from vaporizing your $12 chip that you just spent a bunch of time soldering down.
The other thing to note is that the exposed paddle on the bottom of the part is the main pathway to remove heat. The exposed paddle must be soldered to the PCB and you aren't going to do that with your 30-Watt soldering pencil. You will need SMT techniques: solder paste, a pre-heater for the bottom of the PCB and then do a sort of manual solder reflow with a hot air blower/pencil (unless you have access to a reflow oven).