ULTRA-HIGH-FREQUENCY (UHF) RFID readers based on discrete components are bulky and expensive while consuming a lot of power. Now, researchers have proposed a highly integrated, single-chip CMOS UHF RFID reader transceiver that consumes just 203 mW. The transceiver, which covers the Chinese local standards spanning 840 to 845 MHz and 920 to 925 MHz, was developed by: Le Ye, Huailin Liao, Chen Li, Chuan Wang, Congyin Shi, Junhua Liu, Ru Huang, and Yangyuan Wang from Peking University; Fei Song from Mediatek, Inc.; Jiang Chen from the CEC Huada Electronic Design Co.; Jinshu Zhao from Dresden University, and Ruiqiang Liu from Marvell Technology Shanghai Ltd.
The CMOS transceiver integrates a Class AB power amplifier (PA) with +22 dBm output power and 35 percent power-added efficiency (PAE). At that PA output power level, the reader transceiver exhibits sensitivity of 79 dBm including the directional coupler's 15-dB loss. The transmitter's spectrum mask achieves an adjacent-channel power ratio (ACPR) of at least 45 dBc and as good as 60 dBc, depending on test conditions. To achieve phase noise of 126 dBc/Hz at 1 MHz offset from the carrier and frequency resolution of 1 kHz, the design implements a sigma-delta, fractional-N phase-locked-loop (PLL) frequency synthesizer with a single LC voltage-controlled oscillator (VCO).
The single-chip transceiver dissipates 203 mW from a 1.8-V supply when transmitting +7.5 dBm output power. To compensate for the large selfjammer in the transceiver, the researchers proposed an on-chip self-jammer-cancellation (SC) circuit with a fast time-varying cutoff frequency and a DC-offset-cancellation (DCOC) circuit. See "A Single-Chip CMOS UHF RFID Reader Transceiver for Chinese Mobile Applications," IEEE Journal Of Solid-State Circuits, July 2010, p. 1316.
