CCU #205: FD25E Frequency Doubler

#ComponentsCloseUp No. 205: Frequency Doubler
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*** Quick Facts! ***
Manufacturer: MACOM
Part Number: FD25E
Cost per Unit: $181.92 (Digikey)
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As said above, this part is a frequency doubler, which is a type of component more generally referred to as a frequency multiplier. As the name suggests, it takes an input frequency signal and outputs a multiple of what comes in, or a harmonic of the input frequency. This particular part will double any input frequency in the range of 5 to 2400MHz. Over this range of frequencies, the output will typically be 13 dB less than the input.
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When I initially saw this part I expected there to be a chip inside of it, given its appearance. As I found out, looks can be deceiving! Inside there are a few passive parts that make up the frequency doubler circuit. According to the datasheet, this part includes a Schottky bridge quad diode, along with some ferrite baluns, and that's basically it. The parts are fixed into place and connected together with some enamel wire.
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I would recommend the wikipedia page on “Frequency Multipliers” for more information about how they work.

[DXABOF]

Cool! Amateur radio operators still build double balanced mixers from scratch. It is still the best way to do high linearity receiver mixers. A DBM and a doubler is built and looks almost the same. And as someone else said: they don’t work if you don’t terminate them correctly, both at source and load.

[WolfmanDude]

Looks like a homemade double balanced mixer! I really like that you actually tried it out!

[Goldfinch]

This content is so interesting, it's like opening magic boxes

[Madams]

I’m learning about building antennas and this was so cool to see that the same techniques used for HF radio antennas is used in small form for RF input/output at the transceiver level

[newmonengineering]

You probably need to impedance match the output of the signal. The rf going in is fine but on the output side it is likely reflecting and causing distortion.

[lbochtler]

a few quick points, this is in essence a diode bridge mixer, if you send the same singnal into both input ports, you get the original signal as well as half and double the original frequency out the output. if you only want the doubled frequency, you then need either a high pass or bandpass filter on the output. this is what the rest of the components you desoldered where used for. It should be noted, that this all needs to be impedance matched

edit: a word

[Brandon-veo]

Hello Sir, im a regular person but i have a hobby of breaking down electronics to see how they operate... Thank you i watch your content and you are most informative

[pdotzdb]

Love me classic passive parts like this! All kinds of wonderful RF stuff!

[JohnSmith-jlfm]

Love watching these decapsulations and break downs. 👌

[Daniel-irki]

Did you terminate it with a matched impedance? That might be why you are seeing signal distortion (if you are feeding directly into a high impedance passive probe)

[rubenleal]

Funny... I worked for MACOM back in early 90's. Brings back memories...

[rstechph]

The electronics manufacturing industry is among the most significant contributors to the manufacturing output in the Philippines

[JustinToledojr]

I've been a mechanic since the 90s doing all types of hard mechanic work but that type of work he's doing would make my brains fall out

[BertoldVdb]

The output signal looks as expected. It not just doubles it but also creates some higher harmonics. If that matters in the application, a filter is added behind the module.

[JohnSmith-mfdh]

The frequency got doubled but since you didn't use the auxiliary components, the output signal was crap, I bet the full circuit does a good job, but only the doubler itself won't cut it.

[scotts]

Dont know if I'm the only one who learns from these videos but I just want you to know I love them and please keep them coming.

[notaprofessionaI]

FULL BRIDGE RECTIFIER! Where’s Electroboom hiding?

[ManuelKerres]

Findling an unknown device, opening it up and actuslly understanding what this thing is doing so nice :3

[davidthomas]

It doubles it by creating full wave pulsating DC which makes the peaks 2f. However the output will be distorted as the device is highly nonlinear and you still have pulsating DC out. Assuming you want logic level it would then be run through a low pass and a comparator with hysteresis. If not it would need a dc bias to move the zero crossing down and a low pass as well.

[tariqmehmood]

Being an Electronics Engineer and having a firm grip on knowledge of all these electronic compomemts with an always ready to learn mind. This is what it takes to become an Great Electronics Inventor eventually. Keep it up buddy.

Wish i could meet you... 😊