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OM26630FDK evaluation board RF Field at 60KHz?

Question asked by Mike DeVita on Sep 24, 2018
Latest reply on Oct 2, 2018 by IvanRuiz

Hi, we have a CLRC663 plus NFC Frontend Development kit (OM26630FDK) that we are using to evaluate the NXP CLRC663 plus with the "NXP NFC Cockpit v4.8.0" software. The evaluation board is CLEV6630B v2.0. We are able to poll the MIFARE DESFire card that came with the evaluation kit and are receiving valid codes back after a REQA command issued from the NFC cockpit software. All seems to be working per spec, but we are curious about the source of the 13.56MHz carrier because we are only seeing 60KHz, not 13.56MHz.


The test setup for this is as follows:

  1. We have connected the 30x50mm antenna board with matching network to a coax cable between the RXP and RXN pins of the antenna board. The opposite end of the coax cable has a BNC connector on it.
  2. We connected the BNC connector to a 50ohm input of an MSO oscilloscope.
  3. We place the coax connected antenna board on top of the 65x60mm antenna pattern of the CLEV6630B PCB. With the "RF Field Off" we see no signal on the oscilloscope.
  4. Turning on the "RF Field" we see a 60KHz sine wave with a 4V peak to peak amplitude.
  5. Lifting the 30x50mm antenna away from the 65x60mm antenna pattern reduces the amplitude shown on the oscilloscope (as expected) where at 100mm distance the amplitude is very small.


Why does the "RF Field On" generate a 60KHz carrier and not a 13.56MHz carrier?


Placing the MIFARE card on top of the 30x50mm antenna which rests on the 65x60mm antenna dampens the amplitude by about 0.7V. Sending a REQA command from the NFC Cockpit software still returns a valid sequence from the MIFARE card but the waveform on the scope does not change. What are we missing about the operation of either the NFC Cockpit software?