毫米波卫星接收机收发射频电路设计

【作者】 陈兴华；

【导师】 蔡竟业；

【作者基本信息】 电子科技大学 ， 信息与通信工程， 2007， 硕士

【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。更多还原

【Abstract】 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.更多还原