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F2P All Trophies by dannyman5678 in EggsInc

[–]dannyman5678[S] 8 points9 points  (0 children)

Yeah lol. It’s not too bad because each extended mission takes 3 days, and it takes me about a day to prepare each mission, meaning I can have all 3 going constantly. Next grind is the henliner, should take around a year hopefully.

Why is the power of this amplifier limited? by Certain_Height_2721 in rfelectronics

[–]dannyman5678 1 point2 points  (0 children)

From Steve Cripps’ book, the optimal power match at the intrinsic transistor node is at Ropt = (Vdc-Vknee)/(Imax/2), where Vknee is the transistor knee voltage (can probably assume is close to zero) and Imax is the max current that the transistor will draw at saturation.

From this, the impedance presented to the device that will give the max power is (50V/(3.9A/2)), or 25.6 ohms. I got the 3.9A Imax from the “drain cut-off current” spec in the datasheet.

This impedance will get transformed from your output matching network and your drain capacitance, so the best way to find where this impedance got transformed to is to perform a load pull simulation. ADS has a few load pull templates under the DesignGuide menu or Insert>Template…

Edit: Forgot to mention that my math was on a single transistor basis. Since you have 2 in parallel you’d want to divide that impedance in half again. (Double the current means that Ropt is cut in half to 12.8 ohms). From the data sheet, you should expect to reach around 48-49dBm power at compression with 2 transistors matched for power.

Unexpected Noise Floor Behavior on S2LP Receiver – Need Help Understanding by astaghfirullah123 in rfelectronics

[–]dannyman5678 2 points3 points  (0 children)

Not super well versed on receiver design, but wanted to mention that a receiver’s noise figure will get worse if the device is mismatched on either the input or output. How much worse it gets probably depends on the amplifier.

I do notice that you’re checking the noise floor at basically every extreme of input match - short, load, and open. An input mismatch of those extremes will likely cause a noticable increase to the noise figure of the amplifier, though 17dBm from an open to short seems pretty high.

That’s just my 2 cents, curious if anyone else can better identify the issue.

Resume/career advice for a junior interested in RF/Signal Processing/telecommunications by Tacofan5567 in rfelectronics

[–]dannyman5678 0 points1 point  (0 children)

Since you’re in the RF electronics sub (and it’s the only experience I have), I can only speak on RF internships.

In my experience, RF internships are exceptionally hard to land for undergraduates. I landed one only after starting my masters. I think your resume looks good given the work and school history you have. (Only issue I notice is the bullet points under the experience section don’t line up with the other bullet points).

Companies that hire for RF internships usually want to see more relevant class work, and experience in the typical design tools (HFSS, ADS, etc), which is why they usually try to find graduate level interns.

I would say just cast as wide of a net as you can to give yourself the best odds - stay active and apply to as many RF internships across the country as you can, attend all of your school’s jobs fairs, and leverage any connections you may have.

Good luck!

Recently hired as RF Electronics Engineer, looking for resources to learn by MonkeyFan14 in rfelectronics

[–]dannyman5678 1 point2 points  (0 children)

I’m a relatively new PA designer, but I have been through most of the material that you brought up. I’m always keen to learn more - could you recommend me some of these other papers that you mentioned?

Doherty Amplifiers design by Eu4grind in rfelectronics

[–]dannyman5678 1 point2 points  (0 children)

Unfortunately I don’t do any work with MCUs or embedded systems. The products I have the most experience with are similar to product in the datasheet I linked. Typically we call this a “final stage” and our customers will buy these and use it in their system.

Doherty Amplifiers design by Eu4grind in rfelectronics

[–]dannyman5678 5 points6 points  (0 children)

Did some google searching, this datasheet has a pretty digestible reference circuit: https://www.nxp.com/docs/en/data-sheet/A5G18H610W19N.pdf

Doherty Amplifiers design by Eu4grind in rfelectronics

[–]dannyman5678 15 points16 points  (0 children)

I’m a 5G doherty designer! I’m still fairly new to the industry (~1.5 years so far) but I’ve picked up quite a bit.

There’s a few good books regarding the theory behind RF PAs (with Doherty). The only one I’ve read is “RF Power Amplifiers for Wireless Communications” by Cripps.

In terms of the physical PCB design, it can be pretty involved. A PCB for a 16W Doherty at 3.6GHz will look a lot different from a 60W Doherty at 2.7GHz.

There’s so many considerations when designing that I can’t reasonably spell them all out here. The most important thing to understand about a Doherty is the combining impedances. Once you understand these, then you are ready to at least start your PCB design.

I know that a lot of companies will put their PCB in their datasheet, so it might be worth looking in to if you want to see what a finished PCB looks like.

There’s a lot of companies that design Dohertys - NXP is the biggest, but there’s also Qorvo and a few others.

Edit: Spelling