An UHF RFID transponder with novel clock generator and demodulator

A UHF Radio Frequency Identification (RFID) transponder complying Chinese UHF RFID band setting is presented in this paper. The RFID transponder is composed of analog-RF front-end and digital signal processing unit. The analog-RF front-end is mainly made up of voltage multiplier, limiter, power on reset (POR), clock generator, demodulator and modulator. This work proposes a novel clock generating scheme with features of area effective and high precision which uses common ring oscillator and counter, accompanying reference time interval sent by reader before data communication. Clock generator drives transponder with clock variation of ±1.76% which is below ±15% in ISO 18K-6B. Besides, a new demodulator is presented in this paper. Silicon area occupied by demodulator is only 21% of traditional structure and it could demodulate input signal with data rate ranging from 10Kbps to 870Kbps. The chip area without test pads is 0.7mm2 @ 0.18um CMOS process and consumes 15uW without Memory.