Design issues regarding ST25R3916B

[FYRSing]

I want to design an NFC device.

I plan to use ST25R3916B as the reader, as well as ST25DV64 and M24SR64 as tags.

I hope it can switch between different protocols in work, including ISO15693 and ISO14443.

When using the ISO15693 protocol, the communication distance is 50cm. When using the ISO14443 protocol, the communication distance is 10cm
I have read other related articles in the community. Can you help me check if there are any issues with my ideas
1. I plan to design two antennas to accommodate different protocols (20x20cm and 3.7x4.3cm)

2. The maximum antenna I can use is 20cm x 20cm. Can I achieve my target communication distance by adding some external circuits (filters, amplifiers)? Is it possible to encounter impedance matching issues when doing so? I see that the chip of the RF power amplifier is single ended, and I think it is not suitable for use in differential signals. Their resistance is usually 50 Ω.

3. Due to the fixed direction of the sensing area during use, specific antennas can be used to increase communication distance.

We look forward to your reply

[Travis Palmer · Accepted solution]

Hello FYRSing,

Our Eval boards allow switching between technologies. 

Using our demo software you can find ISO14443 Type A and B tags as well as Felica, ISO15693 and other technologies.

Nevertheless there is a reason for having different technologies. 

For example ISO15693 is intended for longer ranges - as you mentioned up to several cm. Therefore the data rate is very limited. (only 26.5kbps). This allows the manufacturer to build a very narrow banded antenna with high Q-factor.

ISO14443-A/B for example start at 106kbps. This standard also support 212kbps, 424kbps and 848kbps (known as HBR) and even 1696kbps, 3392kbps and 6784kbps (known as VHBR). To support HBR and VHBR the antenna must be very broad banded -  low Q-factor.

To continue, you should first precisely define which technology and which bit-rate and performance you require.

One book delivering a very good overview about the NFC area (and RFID in general) is the RFID Handbook from K. Finkenzeller.

BR Travis

[FYRSing]

I am very happy to receive your reply. I have designed a board according to my idea. If it succeeds, I will share my experience in the community. But I still have a question, how can I buy ST Black Coin mentioned in other posts? I need a label to confirm that it is good to verify my board.

[FYRSing]

At the same time,thank you very much for the book recommendation

[Ulysses HERNIOSUS]

Hi FYRSing,

Not sure if you can still get this older Black Coin tag. 

If you look on st.com for "ST25-TAG-BAG" you will find bags which you can order which contain tags for your reference.

BR, Ulysses