I'm currently working on a RFID Reader that uses the MFRC630 and CLRC663. Also i have a fully working prototype with matched antenna that works very well with different tags, sizes and distances.
Currently I'm stuck at finding the correct External Rx Components.
In AN11019 in Section 4.4.1 there is described to elect R2A and R2B from a starting value (i used 15k) and increase the resistance to get a Signal that is <=1.7V and >=1.2V
But in my case, changing the resistance does not affect the voltage a lot, from 15k where my Umax was around 2.3V i changed to 27k and now to 39k. Currently Umax is 1.73V and Upp is 1.55V. The change between 27k and 39k the voltage only decreased around 100mV.
Attached is a scope shot of the signal with a passive probe that has 4pF (currently no active probe available). Can the probe be the problem? Do i have a faulty IC? Is it possible that i have to increase the resistance even more?
