I would like to be able to switch one 25 Watt 50-Ohm RF source between two 50-Ohm loads, at up to about a 10 kHz switching rate, continuously. The RF will be at up to 2 GHz. I would like the switching between the loads to take about 3 to 5 us, but not more than about 10 us, and give at least 20 or 30 dB of attenuation toward the unselected load when fully switched. And the insertion loss between the source and the selected load should be as low as possible, and no more than 3 dB, but preferrably less than 1 dB.
Is it possible?
If it's possible, does anyone know of a commercially-available unit that already does that? Or, how difficult would it be to design and build one? I assume it's not going to be as simple as just a couple of MOSFET switching circuits. What types of devices might be used?
Also appreciated would be pointers to any datasheets or appnotes that might be relevant.
That's a great place to start if you have never used PIN diodes before. Agilent also has good app notes (from the HP days).
Once you get the hang of it PIN diodes are really cool and cost-efficient RF switches. Just keep rectification effects in mind, especially at higher power levels. I'd try to find some with long carrier lifetimes in the microsecond range, but that depends on what your lowest frequency will be.
No, it doesn't. I routinely save PDF files from my Netscape 4.78 news reader program that I'm using to read this group . Right click and save link as. I've used it for over 10 years with no problems.
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The movie \'Deliverance\' isn\'t a documentary!
On a sunny day (Sun, 06 Dec 2009 17:29:08 +0000) it happened Baron wrote in :
Dunno, different newsreader I suppose.. I just cut and paste the link, although NewsFlex is able to get it by itself. Indeed, kust tried, I can just add it to the URL list, mark it, and select "get marked URls", and it actually works. Would you believe that? Programmed that 10 years ago, forgot all about it. My newsreader:
formatting link
Much better then anything else really. It can even download websites, but in the last 10 years so many new http things have appeared, that I think that no longer works reliably.
That switch requires +15Vdc at 80mA and +5Vdc at 40 mA; about 1.4 Watts total.
It would be very nice if I didn't have to run any power leads to the switch.
If I'm willing to sacrifice 2 to 3 Watts of the RF, does anyone see any problem with making a small RF-to-DC power supply?
If the RF is a 1-2 GHz sinusoid of 25 Watts in 50 Ohms, that should be about 35.36 V RMS, or 50.0 V Peak (100V P-P). What would be a good way to get that down to 15 VDC/80 mA and 5 VDC/40mA? The only two even-possibly-reasonable ways that I can think of, off the top of my head, are: 1) rectify, smooth, and regulate it to DC and then feed that to a switch-mode supply to produce the 15V and 5V, or, 2) use a step-down RF transformer to lower the peak voltage and then rectify, smooth, and regulate. Option 2 could involve two secondary windings, for both the 15V and 5V, or I could just do 15V and then also regulate it down to 5V, since it's only at 40mA.
I've never done a DC power supply design using an RF input frequency, and have just now started thinking about this. Would there be any/ many "gotchas"? What would be the best path to try to take, here?
IF the required RF step-down transformer would be small, and available off-the-shelf somewhere, then that way sounds simpler.
Now I'm suddenly wondering if there are even any suitable smoothing caps, for those frequencies and voltages. Maybe a motor-run polypropylene? Does anyone have any ideas? Or is there some entirely- different approach that I should look at?
Maybe I should have done some homework, before asking. But I thought that a quick reality check, first, might be very helpful. All ideas and opinions will be greatly appreciated!
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