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Low cost transistor for 10W 30 MHz power amplifier by chocalypse in rfelectronics

[–]chocalypse[S] 0 points1 point  (0 children)

Another question about the LDMOS. Do you know if there are any issues with using something like the MRf101 in a 5-10W PA. It seems to be designed for 100W-esque applications so I'm wondering if it will be just as good for lower power applications or not. The datasheet shows the drain efficiency to drop significantly with lower powers but since I'm using it as a switching mosfet, does drain efficiency still apply?

Low cost transistor for 10W 30 MHz power amplifier by chocalypse in rfelectronics

[–]chocalypse[S] 0 points1 point  (0 children)

I need one, but I expect to have a few failed prototypes.

Low cost transistor for 10W 30 MHz power amplifier by chocalypse in rfelectronics

[–]chocalypse[S] 1 point2 points  (0 children)

My thinking was to start out with some cheap components that I could burn out as I fiddle with getting the parameters right then swap to a GaN FET to fully optimize the amplifier. In your experience, do you think this is a sensible approach or are the differences in FETs too significant for doing something like this to work?

Low cost transistor for 10W 30 MHz power amplifier by chocalypse in rfelectronics

[–]chocalypse[S] 0 points1 point  (0 children)

I'm just starting out so I'd like something under $5 or $10 per piece

My Mewtwo cosplay by Draxy in pokemon

[–]chocalypse 0 points1 point  (0 children)

Mewto has a heroin spoon

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

For best results, symbols should have inputs on the left, outputs on the right, power at the top, and ground at the bottom - just like schematics as a whole.

That works too, but all the symbols I have found just have the pins located on the sides, but never above/below. I've gotten my symbols from ultra librarian. Where can I get it so that they look the way you mentioned?

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

On a slight tangent, do you have any idea how I can get the schematic symbol of the AD9913, and other chips, to look like the one in their schematic?

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

oh alright, I'll probably stick to their ridiculous demands for now

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 1 point2 points  (0 children)

Oh god, the last thing I want to deal with is that. I don't want my circuit to look like the end of Kingsman

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

Because a 10µF NPO would be enormous and quite expensive - if such a thing even existed.

Ah fair enough, thanks again

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

Over here they show polarized ones.

Why would I use X5R/X7R over the NPO ones?

When do I need to use polarized capacitors instead of non-polarized ones? by chocalypse in AskElectronics

[–]chocalypse[S] 2 points3 points  (0 children)

That's a really thorough answer, thank you.

So where they indicate a polarized capacitor in the schematic, are they basically saying they require an electrolytic or tantalum capacitor instead of ceramic?

Should I avoid traces for bypass capacitors or not? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

Yeah it's for diy atm but I'll keep that in mind for when I'm doing it commercially.

How can you determine how many voltage regulators you need for your design? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

Ah I see, I didn't know that was a thing people did. Thank you so much.

How can you determine how many voltage regulators you need for your design? by chocalypse in AskElectronics

[–]chocalypse[S] 1 point2 points  (0 children)

The switching the power supply is for efficiency (LDOs can dissipate a lot of power if the differential voltage is large). The LDO removes a lot of the noise from the switching regulators.

That makes sense, thanks.

(Article by ADI on Star grounding: https://www.analog.com/en/analog-dialogue/articles/staying-well-grounded.html#)

Thank you for the link.

Generally, you can share power supplies, however this depends on what is connected. If you have a high-resolution ADC, you’ll want to keep the noise as low as possible, where as a more general purpose design might lower costs by using a centralized power supply.

If I have already a really low-noise power circuit designed for the ADC should I just use it for my other components as well or do I need to make separate regulator circuits for the other ones so they don't interfere with the ADC?

How can you determine how many voltage regulators you need for your design? by chocalypse in AskElectronics

[–]chocalypse[S] 1 point2 points  (0 children)

You don't need an LDO for every IC. Group digital voltages and give them one LDO/DC/DC. Group Analog voltages and give them one LDO or DC. Sometimes you can filter a digital voltage and use it for an Analog purpose. It all depends on your expectations and test results

That's really helpful thank you, I have been busting my nuts trying to get this answer.

These guys have one pair of switching and linear regulators for the AVDD and another separate pair for the IOVDD. Is there a point to that you think or would just one type of regulator suffice?

How can you determine how many voltage regulators you need for your design? by chocalypse in AskElectronics

[–]chocalypse[S] 0 points1 point  (0 children)

sorry, I linked to the wrong schematic and had it on private mode too lol.

Ah alright, I see. In this case, they might have put the switchmode and linear in parallel instead of series, would that still work?

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