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Liu S.,Peking University | Wang X.,Peking University | Shen J.,Peking University | Wang B.,Peking University | And 2 more authors.
Science China Information Sciences | Year: 2012

A novel direct conversion receiver with low cost and low power is implemented in a 0. 18 μm 1P6M standard CMOS process for a Mobile UHF RFID reader. A highly linear active mixer with low flicker noise and low noise active load is proposed. An efficient and low cost on-chip DC offset voltage canceling scheme is adopted with a high-input-impedance four-input OPAMP to buffer the output of the DC offset canceller (DCOC) block. The receiver has a measured input 1 dB compression point of -2 dBm and a sensitivity of -72 dBm in the presence of the large leakage signal from the transmitter. Only occupying a silicon area of 2. 5 mm 2 and consuming 21 mA from a 1. 8 V supply, the receiver makes the mobile UHF RFID reader to communicate with a transponder in a distance of 1 m conveniently. © 2012 Science China Press and Springer-Verlag Berlin Heidelberg.


Li Y.,University of Electronic Science and Technology of China | Li Y.,University of Hong Kong | Sun S.,University of Hong Kong | Jiang L.,University of Hong Kong | Ye T.T.,Hong Kong Randnter for Logistics and Supply Chain Management Enabling Technologies
IEEE Antennas and Propagation Society, AP-S International Symposium (Digest) | Year: 2012

In this paper, a compact hybrid-integrated microstrip rectangular ring antenna with circular polarization is proposed for RFID reader. By integrating a cross-slotted patch hybrid with a rectangular ring antenna in the same plane, the proposed antenna has the features of circular polarization, compact size, low cost, light weight and unique flexibility for RFID applications. A prototype operating at 915 MHz is designed and fabricated. The measured results agree well with the simulated results. © 2012 IEEE.


Liu S.,Peking University | Wang B.,Peking University | Shen J.,Peking University | Wang X.,Peking University | And 2 more authors.
IET Conference Publications | Year: 2012

For a Mobile UHF RFID reader a fully integrated transceiver, which satisfies the protocols of EPC Class-1 Gen-2, is implemented in a 0.18um 1P6M standard CMOS process. In the receiver, to deal with the large leakage signal, a mixer utilizing BJT paralleling with NMOS as input stage and vertical NPN BJT as switching stage is proposed to achieve high linearity(-2dBm P1dB) and low 1/f noise. Furthermore, an efficient low cost on-chip DC offset canceller (DCOC) with a high-input-impedance four-input OPAMP is utilized. In transmitter, a sigma-delta DAC with a novel single to differential (S2D) is used to reduce the noise of the transmitter. Besides a linear up-conversion mixer and a power amplifier driver are proposed. The transmitter achieves an ACPR1 of -27dBc and ACPR2 of -51.8dBc. Supporting FM0, Miller2/4/8 demodulation and DSB-ASK modulation, occupying an area of 10.24mm2 and consuming 130mA from a 1.8V supply, the transceiver can communicate with a transponder in a distance of 1m.


Yang P.H.,University of Electronic Science and Technology of China | Li Y.,University of Hong Kong | Jiang L.,University of Hong Kong | Chew W.C.,University of Hong Kong | Ye T.T.,Hong Kong Randnter for Logistics and Supply Chain Management Enabling Technologies
IEEE Transactions on Antennas and Propagation | Year: 2011

Several compact, low profile and metal-attachable RFID tag antennas with a loop-fed method are proposed for UHF RFID systems. The structure of the proposed antennas comprise of two parts: (1) The radiator part consists of two shorted patches, which can be treated as two quarter-wave patch antennas or a cavity. (2) A small loop printed on the paper serves as the feeding structure. The small loop provides the needed inductance for the tag and is connected to the RFID chip. The input impedance of the antenna can be easily adjusted by changing loop dimensions. The antenna has the compact size of 80 mm × 25 mm × 3.5 mm, and the realized gain about -3.6 dB. The measured results show that these antennas have good performance when attached onto metallic surfaces. © 2011 IEEE.


Liu S.,Peking University | Wang X.A.,Peking University | Shen J.P.,Peking University | Wang B.,Peking University | And 2 more authors.
Science China Information Sciences | Year: 2014

A novel CMOS transmitter with low TX noise and high linearity is implemented in a 0.18 μm 1P6M standard CMOS process for Mobile UHF RFID reader. Adopting double-sideband amplitude-shift-keying (DSB-ASK) as the only modulation is supported, this transmitter has very low power consumption. A novel analog baseband circuit is proposed to reduce the transmitter noise. With a G″m-cancellation technology, a highly linear up-conversion active mixer and a power amplifier driver are designed. The transmitter has a measured output 1 dB compression point of 13.4 dBm. Occupying a silicon area of about 1 mm2 and consuming 144 mW from a 1.8 V voltage supply, the transmitter makes the Mobile UHF RFID reader communicate with a transponder in a distance of 1 m conveniently. © 2014 Science China Press and Springer-Verlag Berlin Heidelberg.

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