A $C$ -band frequency-modulated continuous wave (FMCW) transmitter based on synthetic bandwidth technique for synthetic aperture radar (SAR) imaging is presented. A 500-MHz narrowband chirp signal is up-converted to two adjacent carriers to obtain 1-GHz chirp at the $C$ -band. The adjacent carriers are obtained through fast switching subharmonic injection locking oscillator (SHILO) technique with 14-ns settling time. For narrowband chirp, a wideband fractional- $N$ phase locked loop (PLL) is used, covering 1.8–2.3 GHz and achieving low in-band phase noise of −115 to 120 dBc/Hz. The proposed technique achieves reconfigurable chirp period ranging from 0.3 to 6.3 ms. It can also be easily extended for wider chirp bandwidth by simply increasing the number of SHILO carriers. The chip consumes 84 mW, while occupying a total active area of 2.24 mm².

中文翻译：

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基于合成带宽技术的C波段FMCW SAR发射机

一种 $C$ 提出了基于合成带宽技术的用于合成孔径雷达 (SAR) 成像的波段调频连续波 (FMCW) 发射机。一个 500-MHz 的窄带线性调频信号被上变频到两个相邻的载波以获得 1-GHz 的线性调频信号 $C$ -乐队。相邻载波是通过具有 14 ns 建立时间的快速切换分谐波注入锁定振荡器 (SHILO) 技术获得的。对于窄带啁啾，宽带分数- $N$ 使用锁相环 (PLL)，覆盖 1.8-2.3 GHz 并实现 -115 至 120 dBc/Hz 的低带内相位噪声。所提出的技术实现了范围从 0.3 到 6.3 ms 的可重构线性调频周期。通过简单地增加 SHILO 载波的数量，它也可以很容易地扩展到更宽的线性调频带宽。该芯片的功耗为 84 mW，同时占用的总有效面积为 2.24 mm ²。