薄膜体声波谐振器温度-频率漂移特性分析

薄膜体声波谐振器(FBAR)的谐振频率会受外界环境温度的影响而产生漂移,对于FBAR滤波器而言,这种温度-频率漂移特性会导致其中心频率、插入损耗、带内纹波等性能发生变化,降低其在电学应用中的可靠性。应用ANSYS有限元分析软件,对一个典型Mo-AlN-Mo结构的FBAR进行温度-频率漂移特性的仿真,在-50⁺150℃温度范围内得到其温度频率系数为-33.6×10-6/℃。通过在FBAR结构中添加一层正温度系数的补偿层,分析了补偿层厚度对FBAR温度-频率漂移特性、谐振频率和机电耦合特性的影响。设计的温度补偿FBAR其温度频率系数为0.872×10-6/℃,比未添加补偿层时有很大改善。     

温补型体声波滤波器设计与制备

基于薄膜体声波谐振器(FBAR)技术的滤波器频率温度系数为(-30～-25)×10^-6/℃,其电学性能受环境温度影响较大,将降低滤波器在全温工作的性能,限制其应用环境,尤其是对滤波器通带插损与矩形系数要求高的应用场合。该文在常规FBAR滤波器中引入正温度系数的SiO₂材料层,通过对滤波器的层叠位置设计及加工工艺等技术的研究,研制出S波段温补型FBAR滤波器器件,其工作频率为3.1 GHz,插入损耗为2.0 dB,带外抑制不小于30 dB,频率温度系数为-0.02×10^-6/℃。     

高频低温漂TC-SAW滤波器的设计

该文设计了一款温度补偿型声表面波（TC-SAW）滤波器,建立了弹性材料及压电材料温度方程,对滤波器的温度场进行仿真分析。通过在压电材料（128°YX-LiNbO₃）上沉积SiO₂作为温度补偿层,降低了滤波器的频率温度系数。为了解决在沉积SiO₂温度补偿层后,谐振器的反谐振频率处出现杂散响应,通过增加电极厚度,降低了谐振器杂散响应对滤波器性能的影响。采用四阶级联提高滤波器的带外抑制。仿真结果表明,设计的TC-SAW滤波器中心频率为2 497 MHz,频率温度系数为-9.89×10^-6/℃,-30~85 ℃工作温度范围内的带内最大插损为1.95 dB,带外抑制大于30 dB,-3 dB损耗带宽大于97 MHz。     

一种窄带温补型声表面波滤波器

该文介绍了一种频率温度系数接近0的窄带温补型声表面波滤波器。该滤波器采用黑化的42°Y-X钽酸锂为衬底,温度补偿层材料采用二氧化硅薄膜,利用化学机械抛光二氧化硅薄膜法获得了平坦表面形貌。制作了温补型声表面波滤波器样品并进行了测试。测试结果表明,该温补型声表面波滤波器的中心频率约1 360 MHz,在-55～85℃内频率漂移仅约390 kHz,频率温度系数约-2×10~(-6)/℃,插入损耗约1.3 dB。     

单晶薄膜体声波谐振器频率温度特性研究

采用离子注入剥离法转移制备了43°Y 切铌酸锂(LiNbO3,LN)单晶压电薄膜材料,以SiO2/Mo作为声反射结构制备了固态声反射型薄膜体声波器件。谐振器工作频率约为3 GHz,LN薄膜等效机电耦合系数达到14.15%。对谐振器的频率温度特性进行了表征,结果表明,尽管LN单晶的频率温度系数为(-70~-90)×10-6/℃,但由于声反射结构中包含有正温度系数的SiO2层,谐振器的频率温度系数降至-18×10-6/℃,这表明固态声反射结构能够有效抑制单晶LN薄膜的温漂,获得低频率温度系数的谐振器器件。     

体声波滤波器的片上测试与性能表征

为了表征制备的L波段体声波(BAW)滤波器的性能,采用射频探针台和矢量网络分析仪片上测试获得了BAW滤波器的S参数;在ADS软件环境下计算了BAW滤波器的各项性能参数。比较实测与仿真得到的S参数曲线,发现:低阻硅衬底会使BAW滤波器的带内插损显著增加;BAW滤波器中各薄膜体声波谐振器(FBAR)单元的薄膜沉积厚度误差会使BAW滤波器的带内波动偏大,且FBAR薄膜厚度较设计值增大时BAW滤波器的中心频率会向下偏移。以制备的一只BAW滤波器为例,测得其中心频率为1 495MHz,带宽为17MHz,带内插损为-46.413dB,带内波动为2.816dB,带外抑制为-72.525dB/-79.356dB,电压驻波比为1.940。该文给出的BAW滤波器片上测试与性能表征方法具有通用性。     

100.450 MHz五次泛音温度补偿晶体振荡器

应用新的温度补偿方法研制了100.450MHz五次泛音温度补偿晶体振荡器,该振荡器由450kHz陶瓷振荡器,100MHz五次泛音晶体振荡器,混频器,晶体滤波器组成。450kHz陶瓷振荡器的输出频率与100MHz晶体振荡器的输出频率混频,滤波,取其和频。直接利用450kHz陶瓷振荡器输出频率对100MHz晶体振荡器进行温度补偿。实验结果表明,在0~70℃该振荡器的频率-温度稳定度<±7×10-7,初步测量相位噪声为-119dBc@1kHz。     

S波段网格型FBAR滤波器的研制

介绍了一种单端口,端口阻抗为50 Ω的S波段宽带薄膜体声波谐振器(FBAR)滤波器,该滤波器采用网格型结构的FBAR滤波器芯片级联巴伦芯片实现.对宽带FBAR滤波器芯片的设计过程、工艺实现过程进行了说明.采用0.35 μm GaAs工艺实现了3～8 GHz频率范围的巴伦芯片,在FBAR滤波器芯片的中心频率处,幅度不平衡度为0.53 dB,相位不平衡度为0.55°.制备的FBAR滤波器通带频率范围为3 100～3 400 MHz,1 dB带宽约为369 MHz,在2 660 MHz和3 840 MHz处带外抑制分别为45.6 dBc和41.3 dBc,尺寸仅为12 mm×7 mm×2.9 mm.将实测结果与仿真结果进行了对比,两者一致性很好.     

S波段FBAR滤波器芯片的研制

采用完全自主的薄膜体声波谐振器(FBAR)滤波器设计、工艺技术,制备了S波段FBAR滤波器芯片。该FBAR滤波器的电路结构为梯形结构,采用一维Mason模型进行了仿真、优化。在工艺上采用空气隙型结构,突破了高c轴取向AlN压电薄膜淀积、精密空气腔制作等关键工艺技术,制备的4节FBAR滤波器中心频率为2 340MHz,3dB带宽为25MHz,中心插损为3.8dB,矩形系数达2.24∶1,输入、输出阻抗均为50Ω,芯片体积仅为1mm×1mm×0.3mm,该性能与同频率、同带宽的介质滤波器性能进行了对比,体积可缩小几千倍,矩形系数优于介质滤波器。     

低温漂薄膜体声波谐振器研究

该文介绍了一种基于空腔结构的温度补偿型薄膜体声波谐振器(TC-FBAR)。通过在压电层上方生长SiO₂温度补偿层,实现谐振器的低温漂。未采用温度补偿的薄膜体声波谐振器,其频率温度系数约为-25×10^-6/℃。通过适当的膜层结构设计,可使其频率温度系数在±3×10^-6/℃。结果表明,由于温度补偿层的增加,导致器件总体压电效应降低,使谐振器的有效机电耦合系数降低。低温漂谐振器的实现,为窄带低温漂滤波器的研制提供了有效的设计和工艺技术支撑。     

C波段WLP薄膜体声波滤波器的研制

该文研制了一种晶圆级封装(WLP)的C波段薄膜体声波谐振器(FBAR)滤波器。采用一维Mason等效电路模型对谐振器进行设计,并使用HFSS对电磁封装模型进行优化,再在ADS中对滤波器进行仿真优化设计,得到阶梯型结构的FBAR滤波器。采用空腔型结构并制备出FBAR滤波器芯片,同时利用覆膜工艺对FBAR裸芯片进行覆膜和电镀等WLP工艺,得到WLP的FBAR器件。测试结果表明,滤波器的中心频率为6.09 GHz,中心插损为2.92 dB,通带插损为3.4 dB,带宽为112 MHz,带外抑制大于40 dB。     

S 波段高性能微型滤波器的研究

应用LTCC多层耦合带状线谐振器和交叉耦合传输零点原理,在改进的三维梳状带通滤波器结构中引入交叉耦合,增强非相邻谐振级间的交叉耦合;在2、4谐振级间引入Z字形导体层,通过调节Z字形控制传输零点位置;同时适当调节加载电容大小,有效减小了滤波器体积,实现了高次谐波抑制、边带陡峭和通带内线性相位.采用低温共烧陶瓷(LTCC)技术设计制作了中心频率为3GHz,通带为200MHz的微型带通滤波器.实验和仿真结果表明,该滤波器的中心频率插入损耗小于2.6dB,阻带抑制高于40dB,边带陡峭,尺寸仅为4.8mm×4.2mm× 1.5mm.成品率高达85％.     

Design of a tapered coaxial resonator filter for mobilecommunications

The authors describe the design, a simple fabrication technique, and performance of a coaxial resonator filter with tapered inner conductors to be used in mobile radios. The effects of coupling, window area, and temperature on the performance of the filter have also been considered. The passband of the filter is 30 MHz with a center frequency of 925 MHz, 1.15-dB insertion loss, 0.8-dB ripple, and 14.7-dB return loss at the center frequency. The resonant frequency and coupling coefficient stabilities with temperature have been measured at 28.38 ppm/°C and 3.5×10^-4/°C, respectively. The 3-dB bandwidth is measured as 32 MHz and a sharp cutoff is observed at -16.5 dB with a bandwidth of 37 MHz for narrow scale and -65 dB with a bandwidth of 84 MHz for wide scale. The fabrication technique developed using a zinc-cast inner conductor and extruded aluminum outer conductor has better reproducibility than the conventional machining technique and is highly cost effective     

基于128°YX-LiNbO3压电材料的DMS滤波器设计

设计了一种基于128°YX-LiNbO₃压电材料的双模耦合声表面波(DMS)滤波器。采用耦合模(COM)模型进行理论分析,得到DMS滤波器的二维器件模型,再采用COMSOL进行二维器件仿真分析,得到单级DMS滤波器。为了消除该DMS滤波器在其低端近阻带附近出现的肩峰,该文提出将DMS滤波器表面覆盖一层SiO₂薄膜,形成温度补偿结构,从而解决低端近阻带附近的肩峰。结果表明,设计的DMS滤波器的中心频率为891.0 MHz,最小插入损耗为-1.29 dB,1 dB带宽为34.0 MHz,相对带宽为3.8%,矩形系数为2.94,带外抑制约为-20 dB。     

A single-chip CMOS IF-band converter design for DVB-T receivers

This paper describes a CMOS single-chip IF-band converter (IFC) which is applied in the analog front end circuitry of DVB-T receivers. The proposed IFC is composed of a down-conversion mixer, an automatic gain controller (AGC), and an anti-aliasing filter (AAF). The down-conversion mixer uses a current folded-mirror technique which converts a 36 MHz intermediate frequency (IF) input into a 4.5 MHz baseband signal. The AGC loop applies a novel digital variable gain amplifier (VGA) basing on a g_m-boosting DVGA (digital VGA). A total of three tunable gain stages are cascaded to provide a 70 dB dynamic range. A temperature-compensated 6th order transconductance-C (Gm-C) filter with digitally tunable bandwidth (6, 7, 8 MHz) is used to constitute the proposed AAF. Moreover, a temperature-compensated circuitry is used to neutralize the AAF's bandwidth drifting caused by the temperature variation.     

Pi型电感耦合LTCC滤波器的寄生感性耦合研究

对二阶Pi型电感耦合LTCC滤波器中各个元件的电容及电感寄生效应进行了分析,提出了一种新的寄生电感耦合分析方法,并根据分析结果设计了一个二阶Pi型电感耦合和一个二阶Pi型电容耦合LTCC带通滤波器,其中,电感耦合滤波器的设计指标为:中心频率2.45GHz,相对带宽32.65%,带内插入损耗2dB,回波损耗18 dB;电...     

膜片上FBAR结构的阵列式伽马辐照剂量计

设计了一种膜片上薄膜体声波谐振器(FBAR)结构的伽马辐照剂量计。采用FBAR替代传统伽马辐照检测元件来实现伽马辐照剂量检测的新方法,并提出FBAR呈阵列式分布的结构,可实现辐照剂量和分布的检测。为了对FBAR进行温度补偿,设计了由SiO2与Si3N4组成的双层复合薄膜,SiO2的温度系数为+85×10-6/℃,与具有负温度系数的压电层进行复合,减小了温漂,同时增加了膜片的强度。给出了两种不同结构的阵列式伽马辐照剂量计详细的工艺路线;可望满足阵列式、高灵敏度、微小型化伽马辐照剂量检测的需求。     

Temperature-compensated film bulk acoustic resonator above 2 GHz

Two different types of temperature-compensated film bulk acoustic resonators (FBARs) are designed, fabricated, and tested. One is formed by integrating FBAR with a surface-micromachined air-gap capacitor, which passively reduces the FBAR's temperature coefficient of frequency (TCF) by about 40 ppm//spl deg/C at 2.8 GHz. With this approach, zero TCF would easily have been achieved if the FBARs were built on AlN rather than ZnO. The other type of temperature compensated FBAR is built on a surface-micromachined SiO/sub 2/ cantilever that is released by XeF/sub 2/ vapor etching of silicon. The Al-ZnO-Al-SiO/sub 2/ FBAR is measured to have a TCF of -0.45 ppm//spl deg/C (between 85/spl deg/C and 110/spl deg/C) at 4.4 GHz.     

A dual-mode complex filter for GNSS receivers with frequency tuning

A fifth/seventh order dual-mode OTA-C complex filter for global navigation satellite system receivers is implemented in a 0.18 fxm CMOS process. This filter can be configured as the narrow mode of a 4.4 MHz bandwidth center at 4.1 MHz or the wide mode of a 22 MHz bandwidth center at 15.42 MHz. A fully differential OTA with source degeneration is used to provide sufficient linearity. Furthermore, a ring CCO based frequency tuning scheme is proposed to reduce frequency variation. The measured results show that in narrow-band mode the image rejection ratio (IMRR) is 35 dB, the filter dissipates 0.8 mA from the 1.8 V power supply, and the out-of-band rejection is 50 dB at 6 MHz offset. In wide-band mode, IMRR is 28 dB and the filter dissipates 3.2 mA. The frequency tuning error is less than ±2%.     

Surface-acoustic-wave bandpass filters on ZnO/Pyrex substrate with zero temperature coefficient

Thick layers of ZnO (5?10 ?m) deposited on Pyrex glass have been investigated in order to realise low-cost and temperature-stable surface-acoustic-wave bandpass filters. We describe the sputtering method used to grow the ZnO layer and we give the measured results of the acoustical and thermal properties for different film thicknesses. A high coupling coefficient (10%) and very good temperature stability (zero first-order and 1 × 10?8/(°C)2 second-order temperature coefficient) are reported. In addition we show results obtained on an 8% 1 dB relative bandwidth filter operating around 110 MHz which demonstrate that this new piezoelectric substrate leads to filters with better properties than those achieved on ST-cut quartz substrate.