I would like some help regarding the attached circuit. It is not a design of mine, but I would, though, like to know the purpose of all these 270pF capacitors. The right connection point of the circuit is for a coil PCB RFID antenna. At the left side, MLX90129 RFID tag IC is intended to be connected (which has a 75pF input capacitance in parallel with the two inputs).
My design for the same circuit includes only R1 and C7, in case more matching between the antenna-coil (that is constructed to have an inductance of around 1838nH, which in conjunction with the internal 75pF capacitance results in a frequency of around 13.56MHz) and the IC is needed. Are the other 270pF capacitors really needed?
My design for the same circuit includes only R1 and C7, in case more matching between the antenna-coil (that is constructed to have an inductance of around 1838nH, which in conjunction with the internal 75pF capacitance results in a frequency of around 13.56MHz) and the IC is needed. Are the other 270pF capacitors really needed?
