RF Power Amplifier Design

[@tmjromao]

Learning a lot with the academy videos. Reviewing what i learned 20 years ago while doing a bachelor degree in electronics and computers systems. Electronics was my dream but along the way happened to turn to management. Many thanks for sharing your knowledge

[@AltiumAcademy]

Great to hear!

[@glasslinger]

Those chips are very capable BUT DID YOU SEE HOW LITTLE THEY ARE! When I got the parts in the mail I thought they sent me the wrong parts! They are less than a quarter inch square! The pins are 25 mils apart! Just soldering the part to the board takes a lot of patience!

[@johnferrenby7486]

Thanks a lot. Would appreciate if you made a video about impedance matching for RF power amplifiers, since it requires specific Zin and ZL

[@Zachariah-Peterson]

That's a great topic, it requires a technique called load-pull analysis when working close to saturation. The premise is that near compression, maximum power transfer occurs when there is a slight impedance mismatch between the amplifier and load. I'll have to figure out a way to do it without ADS.

[@mehmetaliozaslan9569]

First of all, I would like to thank Zach Peterson for his valuable videos. We want to operate amplifiers at the P1dB compression point, we know that. Let's say we want the amplifer to not saturate. What protection measures can we take for this? Should we use limiters, drivers, isolator, attenuator or something else?

[@fratg.8213]

I think, using Attenuator will fix the problem.

[@Zachariah-Peterson]

If your power being given to the amplifier is too high then you would need an attenuator, or you need to bring down the power output of the source. In an earlier version of this module that was done for a client, we had a different amplifier with higher gain but lower saturation, and we had to put an attenuator on the source to make sure there was no saturation.

[@ericpilboue3276]

J'en suis qu'a la moitié, avec les sous-titres et votre prononciation, c'est un des meilleurs cours sur yt. In the past, i have heard mrf317 singing audible vibration when my boss was according 88-108mhz fm amplifiers. 😮 Never seen something about this sound on youtube.

[@ChefNongak]

Great video. I just want to point out that usually, the P1dB is refered as an output power rather than an input power (at least by many PA manufacturers). So on your graph, it would actually be the value on the Y-axis rather than the X-axis. Still, keep up the good work!

[@Zachariah-Peterson]

I usually see that in the Hittite datasheets for example, they will show an output P1dB vs. frequency curve so you can see where the P1dB starts to drop out to lower power.

[@pcbworks]

Fantastic!! Informative!

[@AltiumAcademy]

Glad you think so!

[@jimjjewett]

I really hope Google indexes on the captions, and starts sending classicists to this video about a "Hittite microwave".

[@spehropefhany]

Visigoths have entered the chat.

[@Zachariah-Peterson]

Maybe the captions will start to appear in ChatGPT-generated Hittite poetry

[@botsuzuki8129]

I really appreciate it for your guys help

[@botsuzuki8129]

Korean translation 😄

[@sloth4urluv]

I'm assuming there is currently no way to do it in Altium, but one of my wish list items in the schematic would be being able reference specific component parameters as variables in text strings. For example in the schematic you had formulas written out for the voltage of the supplies based on the feedback resistors, it would be nice if you could grab the resistor values and write a formula that auto calculates the values. It would be especially useful for projects that have variants with different values.

[@changpuak]

Nice presentation, but already covered by thousands of textbooks. Stand out of the crowd by revealing the tricks on how to increase the output power ...

[@MrMarsjano]

It`s not like an amplifier always have to work in a linear region. Many amplifiers experience gain decrease due to high temperature. When you drive your amplifier above P1dB gain/output power should be more stable. This phenomenon should be taken into account especially when you are designing multistage amplifier. I would love to see how to implement a flange mount amplifier or any other flange mount component into Altium PCB project (how to properly prepare footprint in .pcblib for it).

[@Zachariah-Peterson]

That's true there is no requirement to always be in the linear region but the intermodulation product issues with FM signals demands working more in the linear range.

[@sanjikaneki6226]

How do you chose a proper anntena? or a proper connector as in SMA might be good enough but should i use it or go for i dont know.... Also one of those amplifiers had the gain set by an analogue voltage how should we approach it ? is a DAC+buffer ok? Also both had some current that you needed to measure is a shunt ok in this use case?

[@Zachariah-Peterson]

If you are selecting an off-the-shelf antenna, you can use the return loss spectrum from the datasheet. From this graph, you will be able to see the Tx/Rx bandwidth and the peak broadcasting frequency. The return loss spectrum is equivalent to the S11 data and it tells you how closely the antenna's impedance is matched to a 50 Ohm input impedance. If you are designing an antenna, such as a printed antenna, then you need to simulate the antenna with a field solver or you have to rely on equations that predict the impedance/bandwidth for the antenna. SMAs are standardized connectors for external antenna modules and for connections between RF modules, I do not have their useful frequency limit memorized but the limit is pretty high.

[@Zachariah-Peterson]

I have never used a DAC + buffer to generate such a voltage, usually it would be done with an adjustable regulator circuit. I would say not to use a shunt element for the current because now you would be loading down the load and the current you measure will not be equal to the current you deliver to the load.