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Frequency dependent switch

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natnoraa

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Hi gurus,

I would like to create a switch that is dependent on specific input frequencies ie

4 switches and 2 paths. Depending on frequency.

f1 (say 2GHz) - turn on only switch 1 and connect both the input and output
f2 (say 3GHz) - turn on only switch 2 and connect both the input and output

so on and so forth

Depending on which frequency it is, it will connect both the input and the ouput. I don't suppose a simple energy harvesting circuit with rectifier works?

Best Regards,
Natnoraa
 

SunnySkyguy

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This might be accomplished using ceramic MLM resonators or large terribly precise high Q helicoils to rectify and cascade charge pump doublers to bias PIN diodes used as RF switches, but then you have not enough power to drive the LNA or Tx unless in very close proximity or perhaps unsafe levels of RF on the eyes.

yet this is what they attempt with distributed wifi repeaters with lower f power for wireless charging. The coil must be bigger than the gap for efficient coupling yet too small for uwave f.
 

natnoraa

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thanks volker and sunnyskyguy.

@volker, nope i am not looking for a diplexer.

@sunnyskyguy, i roughly get what you're pointing at. However, I am doing an on chip design using 65nm cmos process. FET will be a good candidate to implement the switches but it isn't as easy as using a voltage control to bias them

switch.PNG

Apologies for the poor drawing but the idea is thereabout. Each of the frequency will control and connect both the input and the output. If say 3.5Ghz is detected, the rest will be isolated but the '3.5GHz path' will be connected

Cheers,
Natnoraa
 

BigBoss

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An idea..

You can design a 2.5GHz-5.5GHz discrete aweeping VCO and you may construct a system with a wideband Mixer and a simple IF detector ( IF frequency is arbitary) then you can send the Go-NoGo commands to the switch to select the right path regarding to DC value of the detector.The VCO would work Input Frequency+<Arbitary IF Frequency> at discrete frequencies.

Another smart idea may always be found.
 

volker@muehlhaus

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View attachment 117528

Apologies for the poor drawing but the idea is thereabout. Each of the frequency will control and connect both the input and the output. If say 3.5Ghz is detected, the rest will be isolated but the '3.5GHz path' will be connected

Why not use diplexers/multiplexers/filters for this? Your detection & switch idea sounds like a complicated solution to do the same thing, with many difficulties (what if multiple input signals are present?)
 

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