Research On The Novel Radio Frequency Resonator

Radio frequency (RF) resonant devices that include surface acoustic wave (SAW)and film bulk acoustic wave resonator (FBAR) are widely used as high-precisionsensors in biological, chemical, physical and some other relevant fields. Besides, in thefield of wireless communication, high-performance electronic devices based on themare also applied in a number of wireless communication systems. The voltage controlledoscillator is one of the most important blocks in the wireless communication system, theperformancne of LC tanks in them are not easy to improve, and it has been a keyproblem to optimize the LC tanks form the device level. From view of applied range,the thesis further studies thoroughly from the aspects of theoretical modeling, devicedesign and optimization, process fabrication, system integration and testing.Firstly, a6.4GHz SAW resonator is fabricated by employing LiNbO3substrate andnanoscale interdigitated transducers (IDTs). The device design and optimization arecompleted through the finite element method (FEM) simulation to obtain the optimizeddevice structure and size. After this, the nanoscale IDTs are fabricated by electron beamlithography (EBL) with designed process parameters. The fabricated super highfrequency SAW devices are used for atomic-resolution biological detections, achievinga high sensitivity of6.7×10-16g/cm2/Hz and the ability to distinguish single DNA baseand single cell. Besides, the advantages of high repeatability, stable detection structure,low requirements to detected samples and low cost make it a promising device toovercome various defects of existing sensors, which is capable of high applicationprospect for high frequency and high-precision biological sensing.Secondly, from the points of overall systematic performance optimizationand the improvement of CMOS compatibility, we propose the idea of integrationof FBAR resonator and filter with CMOS wireless communication chip. Westudy many critical process such as the fabrication and etching of AlNpiezoelectric film, the fabrication of electrodes, the definition and etching ofdifference-frequency layer, the release of resonant part of device, achievingmany parameters for the fabrication of FBAR resonator and filter and furtherverifying the possibility of integration of CMOS chip with them. Based on this, the parameter optimization, layout design, fabrication process and systematicintegration are completed to obtain a CMOS Pierce oscillator with theintegration of FBAR resonator. Through the serial and parallel combination ofFBAR resonators, we achieve a FBAR filter with a center frequency of2.4GHz,a bandwidth of about60MHz, the insert loss is about0.7dB, the reflectioncoefficient is less than-8dB, and the out-of-band rejection is about47dB witha frequency offset of80MHz from the center frequency. Through the integrationwith the achieved2.4GHz wireless receiver system fabricated with CMOSprocess, the advantages of highly integration, high frequency and ability toprocess high power signal establish a solid foundation for fully integratedwireless RF front-end for the application of next generation.Finally, we conduct a systematic study to improve the power consumption,the noise and other performance of RF voltage controlled oscillator (VCO).Starting from improving the quality factor of passive on-chip inductors and thereducing the area of them, we use nano magnetic material integrated on-chipinductor to replace the regular inductor. Through the optimization of processand material synthesis, we obtain the magnetic material with high permeability,high resistivity and low loss, the introduced material and structure losses arealso mostly avoided. Through the integration of magnetic material into theon-chip inductor with compatible process, the inductance has a gain of49.8%and the quality factor has a gain of59.2%at the operating frequency of1.8GHz.So the area of on-chip inductor has a reduction of26%and the phase noise hasdecreases of20.1dB,7.4dB and1.6dB with frequency offsets of100kHz，1MHzand10MHz. The power consumption of the VCO has a reduction of16.7%andthe achieved figure of merit (FOM) is202dBc/Hz, which is the highest valuecompared with reported similar studies about LC-VCO.