This paper proposes a common gate down conversion mixer with Capacitor Cross Coupling (CCC) technique designed for UHF 900 MHz RFID reader receiver chain. In this work, the common gate (CG) topology in the input stage has been applied to achieve high saturation level to expand voltage swing range. But due to the disadvantage of CG topology, it has poor gain and noise performance. Consequently, the technique of capacitor cross-coupling (CCC) has been adopted to improve conversion gain and noise figure (NF) based on CG topology. The mixer performance with and without the technique of CCC is compared. The operating frequency is 900MHz in UHF band. This circuit has been simulated in cadence Spectre environment and implemented in Tower Jazz 018 CMOS process under 3.3V supply. The simulation results show the improvement on conversion gain and Noise Figure (NF) by 4.5dB and 1.3dB, respectively. And the variations of CCC, from 0.2pF to 4pF, are implemented to get knowledge of performance varying dependent on CC capacitance.

A common-gate down-conversion mixer with capacitive cross-coulping technique for UHF RFID applications

본 논문에서는 900Mhz 대역의 UHF RFID에서 직접변환방식의 LNA/Mixer를 설계하였다. 설계된 회로는 3.3V로 동작하며, 0.18㎛ CMOS 공정으로 구현되었다. 본 논문은 높은 self jamming 신호를 극복하기 위해 공통게이트 입력 구조를 사용였으며, 고이득, 저이득의 두가지 동작 모드를 갖도록 설계되었다. 측정결과, 설계된 LNA/Mixer는 고이득 모드와 저이득 모드에서 각각 4㏈m과 11㏈m 의 입력 p1㏈를 갖고, 12㏈와 3㏈의 변환이득을 갖는다. 또한, 두가지 모드에서 각각 60㎽와 79㎽의 전력을 소비하며, 16㏈와 20㏈의 잡음지수를 갖는다.

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Papers

0.18mm CMOS LNA/Mixer for UHF RFID Reader