A multi-standard analog front-end circuit for 13.56MHz RFID reader

A multi-standard analog front-end architecture SoC (System on Chip) for 13.56MHz radio frequency is proposed. It consists of a transmitter and a receiver. The transmitter adjusts its ASK modulation index with a digitally controlled mode select register, thus supporting RFID standards of ISO/IEC 14443 Type A/B. In the receiver, an envelope detector, a variable gain amplifier and a shaping circuit are introduced. The envelope detector based on operational amplifier can even detector signals with a magnitude of only 100mV. Different gain and compare voltage can be achieved through the variable gain amplifier and shaping circuit which controlled by registers. The proposed analog front-end is implemented in SMIC 0.18um CMOS process at 1.8V single supply. The simulation results indicate the analog front-end satisfies the ISO/IEC 14443 Type A/B standards. The proposed circuit is suitable for RFID reader and NFC transceiver.