I'm implementing a children's game board with 6 spaces to place nfc tags with 6 antennae multiplexed as described in AN6121 - which is a great application note and ideal for what I'm doing! I've done rf and speed layout before but not anything for NFC and I'm a bit confused by a couple of things:
- looking at the photos of the board in AN6121 there seems to be a thick and thin trace going to each antenna, and also a thick trace on the back of the board, none of these look like a differential trace to me, is it just not that critical in this application or am I missing something here? I wondered if the thick traces on opposite sides of the boards were matched to each other?
- secondly I'm reading this "As shown in Figure 14, each antenna has its switching system close to the ports. This matching network is located directly on these ports." to mean the switching should next to the loop antenna, but this would leave 5 pairs of traces to nowhere and stubs are usually bad news with reflections etc, is this right?
lastly i saw this
- "The path between the switching, matching network, and EMI filter should be equalized as much as possible." The reader coils/antennae on this board are placed in a line, so would i be correct to interpret this as a suggestion to zig zag the shorter lines to coils nearer the chip in order to get the length to match?
Any help much appreciated - I'm really keen to get this working!
