超宽带谐波混频器的设计

Design of the Super Broadband Harmonic Mixer

叙述了一种超宽带谐波混频器的原理、设计以及测试结果。该混频器主要由微带线巴伦、倍频器、单平衡混频器三部分组成。按中心频率为4.5 GHz设计出微带线巴伦结构,平衡端口输出相位差180°,具有尺寸小、损耗低、幅度相位一致性好等优点;采用AEROFLEX公司的MSPD2018型相位检波器作为混频器,该混频器采用阶跃恢复二极管倍频器与单平衡混频器并联结构,先倍频n次谐波后再与信号进行混频;传输线为四分之一波长线以提高端口间隔离度;利用微波电路仿真软件ADS对混频器进行基波和谐波分析。测试结果表明,在3～25 GHz的频率范围内,本振至中频的隔离度优于66 dB,其变频损耗的实测结果满足设计要求,在现有的宽带混频器中具有较好性能。

The theory, design and test of super-wideband harmonic mixer were described. The mixer was mainly consisted of the microstrip balun, frequency muhhplier and single balance mixer. According to the central frequency of 4.5 GHz, the microstrip balun coplanar structure was designed. The balance output port phase difference is 180°, and the advantages of small size, low loss, the amplitude and phase consistency were possessed. The phase detector of the AEROFLEX＇ s MSPD2018 was used as the mixer, which uses the parallel structure of step recovery diode frequency multiplier and the single balanced mixer, and the signal mixing with harmonics doubled n times. To improve the isolation of the port, the high-impedance was adopted as line transport line. The fundmental wave and harmonic wave of the mixer were analysed by the ADS which is a simulation software in the microwave circuit. The test result shows that the insulation of the mixer is more than 66 dB in the whole working frequency form 3 -25 GHz, and the conversion loss is satisfied with the data of the designing. As a result, the super-wideband harmonic mixer have better performance compared with others.