An active inductor (AI) based on a cascade gyrator for 30 GHz applications implemented with a 0.25 μm in SiGe technology is presented. The gyrator converts not only a key capacitor into an inductor, but also an added resistor, into a negative resistor. This gyrator-RC has its losses compensated by the negative resistor improving the active inductor Q factor. Changing the bias voltage and current allows to obtain a variable AI. A study of a cascade gyrator AI topology is done to understand the circuit behavior and key elements. For this purpose, an AI impedance model is introduced and discussed. An improved AI with the added resistor replaced by a voltage controlled mosfet resistor is proposed. This extra control voltage allows the variable AI quality factor fine tuning. Schematic and circuit extracted from layout simulations are presented, and compared with the measured results of two prototypes of the AIs (one with a fixed resistor and other with a voltage controlled resistor). A prototype of a high pass filter using the AI with fine Q control was fabricated. Non-linear simulations for different input signal levels were performed and compared with measurements. Also discussion on the non-linear models accuracy is performed.

基于级联回转器30 GHz的应用的有源电感器（AI）与0.25实施 μ介绍了SiGe技术中的m。回转器不仅将关键电容器转换成电感器，还将附加的电阻器转换成负电阻器。该回转器-RC的损耗由负电阻补偿，从而改善了有源电感的Q因子。改变偏置电压和偏置电流可以获得可变的AI。进行了级联回转器AI拓扑的研究，以了解电路行为和关键要素。为此，引入并讨论了AI阻抗模型。提出了一种改进的AI，增加了电阻，并用压控mosfet电阻代替了该电阻。这种额外的控制电压可实现可变AI品质因数的微调。给出了从布局仿真中提取的原理图和电路，并与两个AI原型的测量结果进行比较（一个带有固定电阻，另一个带有压控电阻）。使用具有精细Q控制的AI制作了高通滤波器的原型。进行了针对不同输入信号电平的非线性仿真，并将其与测量结果进行了比较。还讨论了非线性模型的准确性。