A novel integrated amplitude-shift keying(ASK) demodulator for passive RFID tags was proposed.This demodulator,which employs edge-detection technique,is capable of detecting ASK signals with small modulation depth.The circuit is simple and adaptable to different protocols,and it is designed in 0.18 μm CMOS process.Simulations show that the circuit can operate at a supply voltage down to 1 V with 0.5 μW static power dissipation.The minimum difference between high and low levels of the detectable envelope signal is 70 mV. The minimum detectable pulse width is 2.5μs when the rise and fall time is 0.1μs.