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在THz雷达系统中,接收前端工作频率达百GHz,使得中频信号的“灵敏度”和“选择性”矛盾加剧,两级下变频结构的接收机能够有效地解决这个问题,第一级下变频选用高的中频有利于提高信号灵敏度、第二级下变频选用较低的中频则可使信号具有较好的信道选择性。本文基于此应用背景实现了第二级下变频四通道接收单元的模块化设计。测试结果证明该接收模块具备本振频率可变、基带低通滤波器频率可调、宽动态范围等优良拓展特性,这些特性满足某雷达系统对第二级下变频单元的要求。本设计验证了THz雷达系统变频单元模块化设计的可行性,为雷达系统模块化设计提供了有力的支持。
In the THz radar system, the receiver front-end operating frequency of up to 100 GHz, making the intermediate frequency signal “sensitivity ” and “selectivity ” increased contradictions, two-stage receiver of the down-conversion structure can effectively solve this problem, the first The use of high-IF down-conversion high frequency signal is conducive to improving the sensitivity of the second frequency down-conversion of the lower IF can make the signal has good channel selectivity. Based on this application background, this paper implements the modular design of the second-stage downconverting four-channel receiver unit. The test results show that the receiver module has such excellent characteristics as variable local oscillator frequency, adjustable frequency of baseband low-pass filter and wide dynamic range. These characteristics meet the requirements of a radar system for the second-stage down-conversion unit. This design verifies the feasibility of modular design of THz radar system frequency conversion unit and provides strong support for modular design of radar system.