2.45 GHz方向回溯天线系统的宽带小步进本振源

发布时间：2018-02-14 15:59

本文关键词： 相位共轭方向回溯宽带压控振荡器锁相环宽带低通匹配　出处：《江苏大学》2017年硕士论文　论文类型：学位论文

【摘要】：方向回溯天线完全依靠模拟电路快速、自动地跟踪来波,相位共轭方向回溯天线系统可以有效抑制多径效应,在远场和近场区都可以完成信号的回溯功能。在方向回溯天线的研究中,针对通信系统传输信息量日益增大、数据传输速率逐步提高的通信现状,本文为ISM中2.420~2.4835GHz频段方向回溯天线展宽频带研发宽带小步进本机振荡源,给平衡结构外差混频电路提供射频两倍频的本振信号。由于实际振荡器稳定振荡后初始相位随机,短距离移动通信中需要近场回溯,为此从天线波束重定向时延条件和方向回溯阵阵元相位关系推导广义相位共轭原理,证明非平面波条件下的相位共轭仍然成立,并设计4.5~5.3GHz更大选择范围的压控振荡器。电感电容压控振荡器主要由负阻网络和谐振电路两部分构成,依据负阻能量补偿原理和微波网络的S参数特性设计了包含场效应晶体管有源偏置、反馈阻抗、高频扼流和输出匹配网络的负阻电路;利用变容二极管和电感并联构成了宽频调谐的LC谐振网络。在直流偏置FET栅极加入微带开路短截线的反馈元件,提高场效应晶体管满足振荡所需的潜在不稳定性。根据FET有源回路的输入阻抗确定振荡电路的输出负载网络,由于负载网络是非50?的标准终端,故在有源回路和负载网络间设计一个宽频带Chebyshev低通匹配电路来获得电路的最大振荡功率。选择满足调谐范围的变容二极管,设计变容二极管对的反串电路使得谐振网络中二次谐波为零,降低谐波影响、稳定电路。在电路获得稳定振荡后,为改善输出信号的频谱纯度,在振荡器输出端添加平行耦合微带带通滤波器电路。将谐振网络、负阻网络和滤波电路联调优化,获得了调谐电压为0.9~10 V时输出振荡频率为4.5~5.3 GHz的线性调频,调谐灵敏度约为112MHz/V,在输出频率中心频点4.9GHz处,相位噪声为-104.8dBc/Hz@100kHz,-118.8dBc/Hz@1MHz,满足宽频低噪特性。为了维持压控振荡器的稳定性,将压控振荡器加入锁相环,解析环路滤波器各参数,并通过仿真优化确定系统环路带宽为1.25MHz,开环相位裕度为51.567,此时,测试锁相环电路获得中心频点4.9GHz的快速锁定,锁定时间为120μs,电路稳定、精度高,满足方向回溯天线对本振源的要求。
[Abstract]:The directional backtracking antenna completely depends on the analog circuit to track the incoming wave automatically. The phase conjugate directional backtracking antenna system can effectively suppress the multipath effect. In the research of directional backtracking antenna, in view of the increasing amount of information transmitted by the communication system and the gradual increase of the data transmission rate, the signal backtracking function can be completed in the far field and near field. In this paper, a wide band wide band wideband small step local oscillator source is developed for the direction traceback antenna of 2.420 and 2.4835 GHz in ISM, and the local oscillator signal of RF double frequency is provided to the balanced heterodyne mixing circuit. Because the initial phase of the actual oscillator is stable and oscillating, the initial phase of the oscillator is random. In short range mobile communication, the near field backtracking is needed. The generalized phase conjugation principle is derived from the time delay condition of antenna beam redirection and the phase relation of directional backtracking array elements. It is proved that the phase conjugation still holds under the condition of non-plane wave. A voltage-controlled oscillator with a larger selection range of 4.5 ~ 5.3GHz is designed. The inductively capacitive voltage-controlled oscillator is mainly composed of a negative resistive network and a resonant circuit. According to the principle of negative-resistance energy compensation and the S-parameter characteristic of microwave network, the negative resistive circuit including active bias of FET, feedback impedance, high-frequency choke and output matching network is designed. A broadband tuned LC resonant network is constructed by using varactor diodes and inductors in parallel. Feedback elements with microstrip open cut lines are added to the DC offset FET gate. The output load network of the oscillating circuit is determined according to the input impedance of the FET active circuit because the load network is non-50? Therefore, a broadband Chebyshev low-pass matching circuit is designed between the active loop and the load network to obtain the maximum oscillatory power of the circuit. In order to improve the spectral purity of the output signal, the second harmonic in the resonant network is zero, the harmonic effect is reduced, and the circuit is stabilized by designing the circuit of the varactor diode pair. A parallel coupled microstrip bandpass filter circuit is added to the output of the oscillator. By optimizing the resonant network, the negative resistance network and the filter circuit, a linear frequency modulation (LFM) with the output oscillation frequency of 4.5 GHz is obtained when the tuning voltage is 0.910 V. The tuning sensitivity is about 112MHz / V, and the phase noise is -104.8dBc / Hz-104.8dBc / Hz-118.8dBc / Hz-118.8dBc / Hz-1 MHz.In order to maintain the stability of the VCO, the VCO is added to the phase-locked loop and the parameters of the loop filter are analyzed. The loop bandwidth of the system is 1.25 MHz and the open loop phase margin is 51.567 through simulation optimization. At this time, the PLL circuit can obtain a fast locking of 4.9GHz at the center frequency, the locking time is 120 渭 s, the circuit is stable and the precision is high. It can meet the requirement of the local oscillator source for the direction backtracking antenna.
【学位授予单位】：江苏大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN820;TN752

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