A fully integrated CMOS RF transmitter for UHF mobile RFID reader applications

This paper presents a low power CMOS transmitter for UHF mobile RFID applications, in a 0.18-mum CMOS technology. It uses a directional coupler in front of an antenna to reduce transmitter carrier leakage at receiver front-end and to be integrated into mobile handset with a single antenna. It adapts a direct conversion transmitter and consists of low pass filter, variable gain amplifier, up-conversion mixer and drive amplifier. The transmitter supports both the single-side-band (SSB) and the double-side-band (DSB) modulation for the reader-to-tag communications. This IC consumes only 31 mA in SSB mode and 27 mA in DSB mode from a 1.8 V power supply voltage to provide a 4 dBm output power at drive amplifier. The measured LO leakage, output 1 dB compression point and 3^rd order output intercept point achieve 55 dBc, 4.5 dBm and 14.5 dBm, respectively.