K波段毫米波成像系统接收机前端设计与测试

The Design and Measurement of the K-Band Receiver for Millimeter Frontend

针对被动成像系统中二维合成孔径干涉辐射计(SAIR)的多通道一致性问题,通过以下3步骤进行设计与测试。首先,从原理上给出前端接收机的设计指标;其次,通过模块化设计出一个用于SAIR的被动成像仪的毫米波前端,包括作为关键部件的图像抑制滤波器、倍频链路中的谐波抑制滤波器、倍频链路、具有鳍线结构的低噪放单元及其匹配结构、多芯片模块(MCM);最后,给出各单元电路及整体前端接收机的测试数据。结果表明:模块化设计解决了多通道前端的一致性问题、镜像抑制及谐波抑制问题。其中,测量的接收机增益、噪声系数和两处图像抑制率分别为42 dB、3.5 dB、60 dB及30 dB,接收机群延时±125 ps;各通道同相相位误差在200 MHz带宽内为-4°~4.2°;48个通道间同步误差经消除时钟抖动后为±100 ps,相关系数测量图接近圆形,表明接收机具有良好的线性特性,条纹洗涤项的测试进一步证明了群延时符合设计要求。以上所有参数均说明,该设计方法实现了整个接收机的设计要求。

Aiming at the multi-channel consistency problem of two-dimensional synthetic aperture interferometric radiometer(SAIR)in passive imaging system. Firstly, the design index of front-end receiver is given in principle. Secondly, a millimeter wave front-end for SAIR passive imager is designed through modularization, including image suppression filter as the key component, harmonic suppression filter in frequency doubling link, frequency doubling link, low noise amplifier unit with fin line structure and its matching structure, multichip module(MCM). Finally, the test data of each unit circuit and the whole front-end receiver are given. The results show that the modular design solves the problems of consistency, image suppression and harmonic suppression of multi-channel front-end. The measured receiver gain, noise figure and two image rejection rates are 42 dB,3.5 dB,60 dB and 30 dB,respectively. The receiver group delay is ±125 ps, and the in-phase error of each channel is-4° to 4.2° in 200 MHz bandwidth, and the synchronization error between 48 channels is eliminated after jitter, which is ±100 ps, and the correlation coefficient measurement chart is close to the circle, which indicates that the receiver has good linear characteristics. The test of stripe washing item further proves that the group delay meets the design requirements. All the above parameters show that the whole receiver meets the design requirements.