A compact low power ASK demodulator for passive UHF RFID tags

A Low power Amplitude Shift Keying (ASK) demodulator circuit for passive UHF Radio Frequency Identification (RFID) tag is designed in this paper with several area-saving techniques. Current source is employed to realize the envelop detector instead of resistor to reduce the area. Differential circuit is inserted into the demodulator to enhance the performance of demodulation. Diode-connected PMOS pair is used to clamp or average the input signal while the area is saved dramatically. The ASK demodulator is powered by on-chip power of 1.8V with current consumption of less than 0.5μA from the rectifier block. The power supply voltage can be reduced further to save more power.