High Q-factor inductors are critical in designing high performance RF/microwave circuits on SOI technology. Substrate losses is a key limiting factor when designing inductors with high Q-factors. In this context, we report a substrate engineering method that enables improvement of quality factors of already fabricated inductors on SOI. A novel femtosecond laser milling process is utilized for the fabrication of locally suspended membranes of inductors with handler silicon completely etched. Such flexible membranes suspended freely on the BOX show up to 92 % improvement in Q-factor for single turn inductor. The improvement in Q-factor is reported on large sized inductors due to reduced parallel capacitance which allows enhanced operation of inductors at high frequencies. A compact model extraction methodology has been developed to model inductor membranes. These membranes have been utilized for the improvement of noise performance of LNA working in the 4.9 – 5.9 GHz range. A 0.1 dB improvement in noise figure has been reported by taking an existing design and suspending the input side inductors of the LNA circuit. The substrate engineering method reported in this work is not only applicable to inductors but also to active circuits, making it a powerful tool for enhancement of RF devices.

中文翻译：

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SOI 上电感器的基板工程，以提高 Q 因子和在 LNA 中的应用

高 Q 因数电感器对于设计基于 SOI 技术的高性能射频/微波电路至关重要。在设计具有高 Q 值的电感器时，基板损耗是一个关键的限制因素。在这种情况下，我们报告了一种衬底工程方法，该方法能够提高 SOI 上已经制造的电感器的质量因素。一种新颖的飞秒激光铣削工艺用于制造带有完全蚀刻处理硅的电感器的局部悬浮膜。这种自由悬挂在 BOX 上的柔性膜显示单匝电感器的 Q 因子提高了 92%。大尺寸电感器的 Q 因数有所改善，这是由于并联电容减少，从而允许电感器在高频下的增强操作。已经开发了一种紧凑的模型提取方法来模拟电感膜。这些薄膜已被用于改善在 4.9 – 5.9 GHz 范围内工作的 LNA 的噪声性能。据报道，采用现有设计并暂停 LNA 电路的输入侧电感器后，噪声系数提高了 0.1 dB。这项工作中报道的基板工程方法不仅适用于电感器，也适用于有源电路，使其成为增强射频器件的有力工具。