Research And Design Of A Mixer And A Voltage-Controlled Oscillator In UHF RFID Zero-IF Receivers

UHF radio frequency identification system has advantages in recognition distance, speed ofcommunication, information capacity and small sizes, so it has been extensively studied andconcerned in various fields. Mixer, voltage-controlled oscillator (VCO), and divided-by-2frequencydivider are three key RF modules in UHF RFID receivers, and the designs have a high value ofscience and engineering.Based on UHF RFID protocols and Zero-IF structure, the performance of the three modules isdetermined, and then the circuits and simulations of three modules are designed by the Cadencesoftware and SMIC0.18μm CMOS process.Firstly, based on the conventional double-balanced Gilbert, the dynamic current injectiontechniques is used to reduce its noise figure. Differential multi gate transistor technology is adoptedto improve the linearity. Combined with these techniques, an improved mixer is presented, and amixer circuit design optimization method is designed. With a1.8V power supply,it not only gets alow noise figure of12.31dB but also a comparable input1-dB compression point of-5.5dBm. Atthe same time, it achieves a conversion gain of12.47dB, with so low a power consumption of7.2mW.Secondly, by4-bit switch-capacitor array structure, a VCO is designed. It which plays a role inreducing the phase noise of the VCO improves the tuning range. This paper studies the followingelimination noise technologies: removing the tail current source, the large filter capacitor and thesecond harmonic resonance filtering. The VCO’s phase noise is-97.73dBc/Hz at100kHz offsetfrom the carrier and-122.6dBc/Hz at1MHz offset from the carrier with a power consumption of9.6mW.Finally, a divided-by-2frequency divider which based on the dynamic loading latch structureis presented. The single-end dynamic loading latch with the single clock input is used in a higherrate of the common-gate structure which replaced the structure of the common source, and therebyit prevents the mismatching of the latch, and avoids the outputs of quadrature,and avoids thedeviation phenomenon of phase and amplitude.