摘要
由于频谱资源的日益紧张,当前对通信、雷达制导、电子对抗以及遥感遥测等领域电子系统的研究已经深入至毫米波甚至更高的频段。而且,随着科技的进步,人们对毫米波系统的性能要求愈来愈高。就毫米波通信系统而言,为了得到较高的通信质量,一般要求系统的本振频率源具有极高的频率稳定度和频谱纯度。另外,在某些特定的环境中,还要求系统能做到小型化。本课题即是基于这个方向,研制出了一种用于卫星通信的低相位噪声,低杂散毫米波收发前端系统。对于毫米波频段的接收、发射系统,本振频率源始终是系统中的技术难点之
一,它对整个系统的性能好坏具有直接的影响,所以一般采用频率合成技术来实现。对直接式频率合成方法,由于输出的谐波和寄生频率分量难以抑制而较少采用;广泛采用的直接数字式频率合成方法,却面临输出频率上限难以提高和输出杂散的难以抑制两个难题。因此,对于微波、毫米波频段的频率合成器主要还是采用间接锁相合成的方法,并基于专用集成芯片来设计。
本文根据课题提出的要求,在对当前常用的接收和发射方案进行了深入的研究之后,完成了对收发前端系统的方案设计,然后通过设计并实现发射模块的本振频率合成源系统,来验证了方案的可行性。
在对相关理论做了详细分析的基础上,我们采用了一种新颖的单本振二次变频方案来做为发射模块的实现方案。该方案采用单本振源来实现二次变频,在保留传统二次变频方案优点的同时,大大降低了本振的实现难度,且更具灵活性。方案中,发射模块的两级本振信号通过对一锁相频率源进行倍频来得到。由于系统对相位噪声指标的要求非常高,所以该锁相频率源的实现成为了课题的难点。在设计过程中,我们分析了锁相环路的噪声模型,并对各单元模块进行了精心的器件挑选、设计和仿真,经过反复的调试最终使系统的具有优良的相位噪声指标,并取得了理想的测试结果。
经过实际测试,发射机系统可将频率为0.95~1.45GHz的已调信号变频至毫米波频段进行发射,输出信号的相位噪声指标优于-81dBc/Hz@1kHz、-88dBc/Hz@10kHz、-103dBc/Hz@100kHz、-115dBc/Hz@1MHz,杂散优于-55dBc。最后,针对本次设计的不足之处,本文提出了一些改进措施,以及文中所采用的一些设计方法,对以后的研究和设计工作均具有一定的参考价值。
Owing to emergency of frequency spectrum resource crsis nowadays, research about electrical system in the field of communication, radar-guidance, electronic countermeasure and remote sensing has been widely developed in the millimeter wave frequency band. As for millimeter wave communication system, it is generally required to have good performance of frequency stability and spectral purity. In addition, miniaturization is also needed in some given environment. Based on this point, the thesis is just about an attempt of developing the transmitting and receiving equipment used in the satellite communication, which have very low phase noise and spur capability.
For the receiver and transmitter in millimeter wave band, local oscillator is always a key problem in communication system and has the direct influence of system. So, it is often realized by using frequency synthesis technology. Because of the harmonic wave and parasitic frequency composition which are difficult to reject, direct frequency synthesis is usually not adopted. Despite being widely used, digital frequency synthesis has to face the problem of upper frequency limit and spur. Therefore, the frequency synthesizer works in millimeter wave band is mostly designed and realized by the way of indirect phase lock frequency synthesis, based on specific integrated circuit. According to the demands of thesis, this paper makes deep study about scheme of current transmitters and receivers firstly. Then the scheme of this thesis is introduced, and the feasibility is also proved, by designing and realizing of local oscillator system of the transmitter.
After researching correlative theory particularly, we adopt a kind of new scheme of frequency conversion using single local oscillator to achieve double-conversion as the scheme of transmitter. It simplifies the realization of local oscillator and at the same time retains the advantages of traditional double-conversion system. This scheme is favorable in system miniaturization and integration, in which the two local oscillator are got by making frequency multiplication to a phase-locked oscillator. For very high request of phase noise performance, realization of the phase locking frequency source becomes key issue of thesis. In the process of designing, noise model of phase locked loop (PLL) is analysed; component selection and parameter simulation of submodule are also performed elaborately. Based on reduplicate hardware debugging, the transmitter possesses excellent phase noise capability at last and testing result is achieved at the same time.
Finally, the transmitter introduced in this thesis can modulate the signal of 0.95~1.45GHz up to millimeter wave band. The phase noise performances of output signal are better than -81dBc/Hz@1kHz, -88dBc/Hz@10kHz, -103dBc/Hz@100kHz, -115 dBc/Hz@1MHz and spur is lower than -55dBc. At the end of paper, aiming at shortcoming of thesis, some corrective measures are proposed. And together with the design method introduced in paper, there are considerable reference value to future scientific research work.
引文
[1] 薛金良.毫米波工程基础.北京:国防工业出版社,1998
[2] 阮成礼.毫米波理论与技术.成都:电子科技大学出版社,2001年3月第1版
[3] 吴正德.中国毫米波技术发展.电子科技大学学报,1991 年六月
[4] 孟庆鼐.毫米波通信的应用及发展.微波与卫星通信,1996,(2):20-23
[5] 张九龙,酆广增.毫米波卫星通信及抗雨衰技术.中国有线电视,2002,(22):55-56
[6] 陈明章.毫米波卫星通信技术.空间电子技术,2002,(4):1-4
[7] 张有正,陈尚勤,周正中.频率合成技术.北京:人民邮电出版社,1984
[8] Zvi Galani. An overview of Frequency Synthesizers for Radars. IEEEtrans.Microwaves Theory Tech.,1991,39(5):782-790
[9] Jwo-Shiun Sun. Design A Frequency Synthesizer For Mobile Communication Systems. Microwaves&RF, 2000.11
[10] J.Tierney, C.M.Rader, B.Gold. A Digital Frequency Synthesizer. IEEE Transactions on Audio and Electroacoustics,1971,19(1):48-57
[11] 梁德文.世纪之交的军民两用毫米波技术.电讯技术,1999,(6):93-97
[12] 赵玉洁.毫米波通信的应用现状和发展趋势.电子展望与决策,1994,(6):17-19
[13] 陈邦媛.射频通信电路.北京:科学出版社,2002,139-154
[14] 钱卫华.高线性大动态范围通用接收机研究与实现:[硕士学位论文],成都:电子科技大学,2003,3-4
[15] 肖志敏.2-30MHz 短波电台射频前端研制:[硕士学位论文],成都:电子科技大学,2005,13 -15
[16] 杨陈庆.专用短波射频射频接收机的研制与实现:[硕士学位论文],成都:电子科技大学,2005,4-5
[17] 高峻.无线通信射频接收前端研究与设计:[硕士学位论文].成都:西南交通大学,2006,5-7
[18] B.Razavi. Design Considerations for Direct-Conversion Receivers. IEEE Transactions on Circuits and Systems-Ⅱ:Analog and Digital Signal Processing,1997,44(6):428-435
[19] 杨小牛,楼才义,徐建良.软件无线电原理与应用.北京:电子工业出版社,2001,64-89
[20] ChenXing-hua, CaiJing-ye, RenWei, etal. Analysis of the Double-conversion Scheme Based on Single Local Oscillator. 2006 6th International Conference on ITS Telecommunications Proceedings.Chengdu:UESTC,2006,1184-1186
[21] 白居宪.低噪声频率合成.西安:西安交通大学出版社,1995
[22] Robins W.P.. Phase Noise in Signal Sources:Theory and Applications.Peter Peregrinus,1982
[23] 万心平,张厥胜,郑继禹等.锁相技术.西安:西安电子科技大学出版社,1991
[24] Roland E.Best. Phase-Locked Loops Design,Simulation,and Applications. Beijing:Tsinghua University Press,2003,23-80
[25] 王福昌,鲁昆生.锁相技术.武汉:华中理工大学出版社,1996
[26] Dean Banerjee. PLL Performance,Simulation,and Design. National Semiconductor,2003
[27] 邓川.小型 Ka 频段锁相源技术研究:[硕士学位论文].成都:电子科技大学,2004:20-21
[28] M.Funabashi, T.Inoue, K.Maruhashi, etal. A 60GHz MMIC stabilized frequency source composed of a 30GHz DRO and a doubler. IEEE MTT-S International Microwave Symposium Digest,1995:71-74
[29] Thomas C.Ho, S.Chen, S.Tadayon. A high-performance W-band intergrated source module using GaAs monolithic circuits. IEEE Microwave and Guided Wave Letters,1994,4(7):241-243
[30] 徐锐敏,张文彬.毫米波锁相倍频源小型化研究.微波学报,2002,18(3):75-78
[31] J.Baprawski, C.Smith, F.J.Bernues. Phase-Locked Solid State mm-Wave Sources. Microwave Journal,1976,19:41-44
[32] 恽小华,恽才华,张国春等.8mm 小型化低相位噪声锁相源.红外与毫米波学报,1995,14(5):383-386
[33] Analog Devices Inc. ADF4106 Datasheet,2005
[34] 清华大学《微带电路》编写组.微带电路.北京:清华大学出版社,1975:171-208
[35] 李在铭,李小峰,周宁等.随机信号分析.成都:电子科技大学出版社,2004:158-172
[36] Alan V.Oppenheim, Alan S.Willsky,With S.Hamid Nawab. Signals and Systems,2nd edition,刘树棠译.西安:西安交通大学出版社,1998:471-519
[37] 陈兴华,蔡竟业,任威等.单本振二次变频方案浅析.电讯技术,2007,47(1):127-130
[38] Bj?rn Bieske, Horst Wei?leder. Flexible Configurable Single Chip Receiver for Low Power Radio Module in 868 MHz Band. IEEE Conference for Circuits and Systems for Communications,2002:304-307