A Digital IF Based UHF RFID Reader Transmitter

A novel architecture of RFID transmitter is presented in this paper which is based on digital intermediate frequency (IF). The design includes digital baseband and CORDIC (Coordinate Rotation Digital Computer) based SSB (single side band) and DSB (double side band) modulator in intermediate frequency. Parameters of this design are compliant with the ISO/IEC 18000-6 type C standard. The digital baseband portion of the design mainly contains a shaping filter and a Hilbert transform filter which are implemented by 14 taps and 21 taps FIR filters respectively. A 12 stages pipeline CORDIC circular rotator is utilized to implement SSB modulation and DSB modulation. Lower power consumption and area occupation come out with this novel architecture as one path of analog front-end including a DAC and a mixer is saved compared with zero-IF architecture. The SSB suppression is better than 40dB and the spurious free dynamic range (SFDR) is better than 70 dB. The time needed for frequency hopping is only 0.19 mu s.