Need help with PIN diode selection in RF switching circuit

[James Demers]

TL;DR

Can I make a passive RFID tag switchable, by inserting a PIN diode into the antenna loop?

I have a project that calls for activating a passive RFID tag by applying a few volts, and a PIN diode seems to be what I need. I can insert it into the antenna loop, where it would prevent an RF signal from being sent unless a forward DC voltage was present. I only know enough about electronics to be dangerous, and I'm hoping somebody can advise me on the appropriate specs for the diode. The spec sheets for these things are baffling: https://rocelec.widen.net/view/pdf/wkwnaj16jm/INFNS15694-1.pdf and there's not a lot of info on low-power applications like mine. (We're talking about the inexpensive 13.56 MHz stick-on tags that they put on retail products.)
Any help would be much appreciated!

 

[tech99]

TL;DR Summary: Can I make a passive RFID tag switchable, by inserting a PIN diode into the antenna loop?

I have a project that calls for activating a passive RFID tag by applying a few volts, and a PIN diode seems to be what I need. I can insert it into the antenna loop, where it would prevent an RF signal from being sent unless a forward DC voltage was present. I only know enough about electronics to be dangerous, and I'm hoping somebody can advise me on the appropriate specs for the diode. The spec sheets for these things are baffling: https://rocelec.widen.net/view/pdf/wkwnaj16jm/INFNS15694-1.pdf and there's not a lot of info on low-power applications like mine. (We're talking about the inexpensive 13.56 MHz stick-on tags that they put on retail products.)
Any help would be much appreciated!

I think you would find the following article helpful. It might be worth considering an FET or CMOS switch for your task as it consumes little power. https://www.digikey.co.uk/en/articl...kGKgjdRRFSKTevpNJAEGdnC5vqDhNQROEnxBRqI5Q9OFc

 

[Baluncore]

TL;DR Summary: Can I make a passive RFID tag switchable, by inserting a PIN diode into the antenna loop?

I can insert it into the antenna loop, where it would prevent an RF signal from being sent unless a forward DC voltage was present. I only know enough about electronics to be dangerous, and I'm hoping somebody can advise me on the appropriate specs for the diode.

You are approaching this from the wrong direction. The RFID tag derives power by rectifying the antenna voltage. It uses diodes to do that. You will need to know the circuit used by your RFID tag before you insert further components in that circuit.

The PIN diodes used in RF switches usually come in pairs. When one is reverse biased, the other is forward conducting. That way, when one diode blocks current, the other allows the signal to pass. That requires a continuous forward voltage or current. Meanwhile, given a sufficiently high RF voltage, your disabling voltage will be exceeded, and the RFID tag will become active.

You might do better by programming a tag to enable or disable transmit.