THT vs SMD components noise

[Paul98]

Hi, I'm designing a small RF amplifier that works around 10Mhz. The question is: Are components such as resistors and SMD capacitors quieter than their analogs in THT? For convenience I would prefer to use THTs which are more comfortable to replace if needed. But the noise? Thank you.

 

[KlausST]

Hi,

I'm using SMD almost exclusively.
Soldering is just a kind of practice.
So I recommend to use SMD .. not because of noise but mainly because of less stray inductance...which plays a big role for HF stability.
(Added And use a really solid GND plane...to reduce noise and get more stable amplifiers.

SMD layouts compared to THM layouts are different, but not necessarily more difficult.

For low cost reflow soldering buy a 10mm thick aluminum plate and a thermometer. Then use your kitchen oven.
Solder paste stencils are cheap now. Adhesive tape, maybe double sided, will be sufficient to fix the stencil on one edge.

Once you get familiar with this you will love it.

Klaus

 

[Paul98]

I remember there was some difference and you reminded me of it. They are the stray inductances. For the ground I would have thought of creating a ground plane in one of the two sides of the PCB so that each SMD component can use it. . Perhaps the best is the components side for this purpose. What do you think about it? I ask you another question: Does the PCB material also have parasitic or other capacities that could differentiate the result from a simulation?

 

[KlausST]

Hi,

with "solid" ground plane I meant solid ground plane. No components, no traces, just GND.
So definitely not at components side. At least not if you are not an experienced HF PCB layouter.

If you are experienced and know about: signal flow, return paths, enclosed (antenna) area, impedances ... then you can use the components side GND - even if cut into pieces.
If you want to be on the safe side: Use the opposite side for GND...and individual vias for every GND connection to the component side.

If you are in doubt: Show your PCB layout, we will comment it.

Klaus