第29卷第4期 红外与毫米波学报 Vo1.29,No.4 2010年8月 J.Infrared Millim.Waves August,2010 文章编号:1001—9014(2010)04—0241—04 MINIATURIZATIoN Ka.BAND RECEIVER USED FoR PASSIVE MILLIMETER WAVE IMAGING GUAN Fu—Hong,rANG Ming・Hui,XU Jie,QIAN Rong,SHI Xiang,SUN Xiao.Wei (Shanghai Institute of Microsystem nad Information Technology,Chinese Academy of Sciences,Shanghm 200050,China) Abstract:A miniaturization of Ka—band direct detection receiver based on monolithic microwave integrated circuit(MMIC) used for passive millimeter wave(MMW)imaging was proposed.This receiver was composed of wideband low noise ampli— iter(LNA)module,small signal diode detector and dc ampliifer.Each module was designed,fabricated,and tested.The performance of the receiver was also tested.The measured results show that the receiver achieves a RF gain above 30dB with noise fiugre less than 3.8dB and an effective bandwidth 7.4GHz.Some MMW images obtmned with this receiver using a horn antenna prove the receiver’s applicability in passive MMW imaging. Key words:passive millimeter wave imaging;millimeter wave receivers;monolithic microwave integrated circuit(MMIC) CLC number:TN957;TN409 Document:A 用于被动式毫米波成像的小型化Ka波段接收机 关福宏, 杨明辉, 许 杰, 钱蓉, 时 翔, 孙晓玮 (中国科学院上海微系统与信息技术研究所,上海200050) 摘要:研制了一种工作于Ka波段用于被动式毫米波成像的基于单片微波集成电路(MMIC)的小型化接收机.该接 收机主要由毫米波宽带低噪声放大器模块、毫米波小信号二极管检波器和视频放大电路组成.设计、制作、测试了 接收机各个组成模块,对接收机的整体特性进行了测试.测试结果表明,该接收机的有效带宽约为7.4GHz、噪声小 于3.8dB、增益约为30dB.应用喇叭天线和该接收机获得的一些毫米波图像表明,该接收机可以应用于被动毫米波 成像. 关键词:被动式毫米波成像;毫米波接收机;单片微波集成电路 中图分类号:TN957;TN409 文献标识码:A Introduction detecting weapons and contraband hidden under people’ s clothing ~ .In recent years.MMW ima ̄ng technol— Various passive MMW imaging systems which ogy has got huge advancement benefited from the rapid measure the apparent temperature of an object via the development of microwave and millimeter integrated cir- energy emitted or reflected from the target objects have cuit(MMIC)and multi—chip module(MCM)technolo been developed for great interest in some biomedical, gY .The most important element of MMW imaging remote sensing,and homeland security applications, system is a single—pixel receiver.Compared with hetero— due to a possibility to penetrate moisture,dust,and dyne receivers made of RF mixer and IF ampliifer,the smoke far better than infrared or visible systems.Fur- direct detection receiver requiirng a low noise amplifier thermore,the ability to penetrate dielectrics such as (LNA)and a detector has many advantages which plastic and cloth has opened up the oppoaunity of become more pronounced in focal plane staring array Received date:2009-03・30,revised date:2010・04-08 收稿日期:2009.03.30,修回日期:2010.04.08 Foudanfion ietm:Suppoaed by the“973”Pmgram(NO.2009CB320207)and Science and Technology Commission of Shanghm Municipality(NO. 08DZ1110500); Biography:GUAN Fu—Hong(1976一),female,Shanghm China,PhD.Research field is RF&MMW integrated circuit.system integrated technology and MMW imaging system. 242 红外与毫米波学报 29卷 system.Up to now,various direct detection receivers had been developed( 】’ This paper presents a MMIC direct detection MMW receiver operating in Ka band in two sections. In section 1,the operation principle is described,each component of the receiver is designed and measured, and the supporting measured data are also presented. In section 2,the performance of the receiver is presen- ted,and some experiments using this receiver have been done to validate its applicability for passive MMW imaging application. 1 Circuit design and performance Detecting the apparent temperature of targets through the energy emitted or erlfected from the objects is the fun- damental of a passive MMW system.Supposing the system noise temperature ≈ To, n fluctuation AG/G=O.the minimum detectable temperature change is △ Fm To/ 晰.(Where is noise fm【p/actⅡ一矗0 or of the erceiver,To is environment temperature, is integral time).A block diagram of a total power idrect detection erceiver is shown in Fig.1.It is made of a LNA with a bandwidth of B and a gain of G,a diode detcetor with a voltage sensitivity of C(v/W),and video ampliifers. The output voltage ofthe receiver is given by =CGG ( + ) . (1) 1.1 LNA module and the MMIC LNA hTe LNA module is composed of two cascaded MMIC chips to provide both enough gain and a RF sig- nal in the square-law region of the diode detector.The f一一一一一一一一一一一1 Fig.1 Block diagram of the direct detection receiver 图1 直接检波接收机框图 Fig.2 MMIC LNA 图2 MMIC低噪声放大器 Fig.3 Photograph of IJNA module 图3低噪声放大器模块 备 Fig.4 Measured gain,noise figure versus frequency of the LNA module 图4 LNA模块增益、噪声测试曲线 MMIC ampliifer shown in Fig.2 has been designed by our group and manufactured with an advanced 0.15 1 ̄m GaAs phemt process.Measured results on wafer show the MMIC LNA has a gain of 15—-17dB and a noise of 2~3dB within the band 26.5—40GHz. In the mechanical design,assembly,and inter— connections special attention was paid to some aspects beyond the basic electircal performance in order to obtain better matching between the LNAs and reduce the ripple in band[ ]because the module is a MMW system.The two MMIC chips are assembled in a gold— iflled box.Fig.3 shows a detail of the modular.Inter- connections between microstrip lines and MMICs are made using 25 m gold wires by ultrasonic bonding. The bonding wires ale as short and low as possible in 0rder t0 minimize the ef et on the LlNA.Bias MMIC networks are composed of a MIM and chip capacitors to sasure ampliifer stability at low frequencies.Signal at input and output comes from two K connecter connec— tion through the microstrip line transition.The module’s measured noise and associated gain are shown in Fig.4.It has achieved a gain of 29~31dB and a noise figure of 3.4—3.9dB for frequency from 30~40GHz. 1.2 Diode detector After the signal is ampliifed,a square-law detec— 4期 GUAN Fu-hong et al:Miniaturization Ka-band receiver used for passive millimeter wave imaging 243 否 Fig.8 Photograph of the receiver Fig.5 Photograph ofthe detector 图8接收机照片 图5检波器图片 目 蓦 l f/Gin lfGm Fig.9 Dependence of the receiver’s sensibility on frequency Fig.6 Frequency dependerce of voltage response of the detector 图9接收机灵敏度对应频率测试曲线 图6检波器探测电压对应频率特性测试曲线 detected voltage suitable for data acquisition electronic tor is designed to convert the MMW singal to dc volt— module.There is often a small dc bias,since the out— age .The detector is composed by a hybrid reactive,/ put voltage of the detector being boosted is so low, passive matching network and a beam.1ead diode there is often a small dc bias,a band pass filter is used HSCH9161.A high—low impedance lowpass filter is to modulate the input singal in order to Jimit the effect used to provide RF ground and a lOOk ̄load resistor is of 1/f noise and keep the ampliifed singal within the used as video load.The input and output microstrip limits of the op—amp and filter power rails.An OP27 network had been manufactured on dielectric substrate precision operational ampliifer is selected as the first with the thickness of 0.254mm and permittivity = 。stage.Connecting to the 0P27.are two LF353 FET op— 2.2.The diode is attached to the microstrip by silver. erational amplifiers which have functions of filtering iflled epoxy・Fig.5 is a photograph of the diode detec— and amplifying the singa1.Video ampliifers was tor.Fig.6 depicts the measured detected voltage versus designed to make the detected voltage suitable for data frequency when the input power is-30dBm.The detec— acquisition electronic module.Measured results indi- ted voltage versus input power at 34GHz and 32.5 cate the video ampliifers a voltage gain about 40dB and GHz,respectively,is shown in Fig.7. a bandwidth of 15~40Hz. ‘1.3 Video amplifiers 2 The receiver performance and experi- Video ampliifers which were designed to make the mental results 2.1 The receiver performance hTe receiver as shown in Fig.8 is formed by con. necting the LNA module,the diode detector and video ampliifers.The receiver’s performance at diferent fre. quencies was measured from 20 to 40GHz for several P0dBm input powers.The sensibility with the一62dBm input Fig.7 Voltgae response versus imput power at two different power is shown in Fig.9.The effective bandwidth of frequencies the receiver is 7.4GHz which was calculated using 图7检波器探测电压对应输入功率特性测试曲线 output voltage values taken at discrete frequencies as in 红外与毫米波学报 29卷 Fig.10 Comparison between optical and passive MMW ima- ges with the designed sensor 图1O光学照片及其用接收机所成的对应的毫米波图像 equation(6)since the receiver is a direct conversion system[ .The system minimum detectable temperature change is less then 1 K calculated using equation(1), supposing =290K, =1 ms.The specifications for the receiver are summarized below in table 1. ,o ( )一 )‘ ’( )…(∑V ’(2) Table 1 The receiver speciifcations 表1接收机指标 System parameter Value Centrefrequency 35GHz RF bandwidth 7.4GHz RF gain(in operation frequency range) 30dB Noise figure(in operation frequency range) <3.8dB Dynamic range —-70~..50dBm Video bandwidth 15~40Hz Video gain  ̄-40dB width 5 degree)by 2-D mechanical scanning.Two of the passive millimeter-wave images are shown in Fig. 10 for metla boards with diferent shape placed at the distance of 100cm from the receiver. 3 Conclusion This paper describes the basic principle of a direct detection receiver,presents the design fundamentals, and tests the performance of each part of the receiver. 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