The MLX90121_FSK is a 13.56MHz RFID transceiver integrated circuit which is ISO compatible and is best suited for most short to mid-range applications. It is user friendly, enabling the modulation depth in write mode to be selected accordingly. Other single sub carriers such as ASK, FSK and PSK modulations are in read only mode. The receiver is based on a diode envelope detector which is followed by an amplifier and IF filter. A logarithmic amplifier used in ASK detection facilitates fast and clean data recovery. An inbuilt open drain output transistor that can provide up to 250 miliwatts of RF power to a 50 Ohms load with a 5 volt power supply is used by the transmitter. For PSK and FSK recovery, the limiting output of the amp is used. The use of a simplified antenna and a matching network is also permitted, albeit at the cost of reduced reading range such as a hand-held reader.