RF and microwave high-Q floating active inductor design and implementation

In this paper, a high-Q floating active inductor (FAI), suitable for RF and microwave applications, is presented. The proposed FAI is based on two cascaded pairs of highly linear capacitance gyrators, which provide a symmetric and reciprocal structure. The proposed FAI shows fully symmetrical two-port characteristics, high quality factor and high linearity. As a feasibility demonstration, a prototype of the designed FAI has been fabricated, together with an LC series band-pass filter. At the operating frequency, the real part of the impedance of the equivalent FAI is very low (Req = 0.0039 Ω), providing a very high quality factor. The filter has a central frequency of 430 MHz and a -3 dB bandwidth of about 9 MHz.