基于GaAs肖特基二极管的330 GHz接收前端技术研究

Development of 330 GHz receiver front-end with GaAs Schottky diodes

基于GaAs肖特基二极管,设计实现了310~330 GHz的接收机前端.接收机采用330 GHz分谐波混频器作为第一级电路,为降低混频器变频损耗,提高接收机灵敏度,分析讨论了反向并联混频二极管空气桥寄生电感和互感,采用去嵌入阻抗计算方法,提取了二极管的射频、本振和中频端口阻抗,实现了混频器的优化设计,提高了变频损耗仿真精度.接收机的165 GHz本振源由×6×2倍频链实现,其中六倍频采用商用有源器件,二倍频则采用GaAs肖特基二极管实现,其被反向串联安装于悬置线上,实现了偶次平衡式倍频,所设计的倍频链在165 GHz处输出约10 dBm的功率,用以驱动330 GHz接收前端混频器.接收机第二级电路采用中频低噪声放大器,以降低系统总的噪声系数.在310~330 GHz范围内,测得接收机噪声系数小于10.5 dB,在325 GHz处测得最小噪声系数为8.5 dB,系统增益为(31±1)dB.

A 310 -330 GHz receiver front-end with Schottky diode was designed and tested. The receiv- er first stage is a subharmonic mixer （SHM）. In order to lower conversion loss （CL） and improve re- ceiver sensitivity, the diode parasitic parameters such as the air-bridges inductance and their mutual in- ductance were discussed. The diode RF, LO and IF port impedance were calculated with embedding a- nalysis for circuit optimization. The simulated CL accuracy was improved. The LO sources was real- ized by a x 6 ~ 2 multiplying chain, in which the sextupler is a commercial active multiplying chip. The balanced doubler was realized by a anti-series Schottky diode mounted on a suspended line. The chain can generate 10 dBm output power at 165 GHz to pump the receiver SHM. The receiver second stage is a low noise IF amplifier for lowering system noise figure. In the frequency range of 310 -330 GHz, the measured receiver noise figure is lower than 10.5 dB with a minimum value of 8.5 dB at 325 GHz. The receiver gain is （31 ± 1 ）dB.