RF active circuit simulating a floating inductance

Abstract

In this paper a new design scheme simulating a floating inductive behavior at RF frequency is presented. The proposed floating active inductor shows a very high quality factor, high linearity and is suitable for many microwave applications and ICs.The design is a fully symmetrical two-port and reciprocal structure, based on two cascaded pairs of highly linear capacitance gyrators. It shows an inductance value of 370nH at 220MHz with a quality factor greater of 6e4.A prototype board has been fabricated with discrete components and tested with successfully results.Index Terms -Active circuits, floating inductors, quality factor, dynamic range, filters.

A Second Order 1.8–1.9 GHz Tunable Active Band-Pass Filter with Improved Noise Performances

“…First, a passive band-pass filter was designed following the Cohn's coupled resonators filter topology [25] to find the values of capacitance C res and inductance L res required, in which the inductor value was established according to the commercial chip inductors available; this allowed for evaluating the behavior of the filter using an inductor with a specific Q, considering the introduced losses. Then, values for the RLC feedback load were chosen, using Equations ( 6) and (7), to ensure that the negative impedance was within the interested frequency range, considering the damping resistance equal to zero; since this range shrinks as the resistance becomes larger, it must be greater than the desired tunability range. Once the values for the feedback load and the resonator parameters were set, we needed to match the active capacitance input admittance with the desired one to achieve the equivalent parallel resistance of the chosen real inductor, which is R loss in (9), so that the input resistance and the input capacitance of the active circuit matched R loss and C res , respectively.…”

“…In the literature, the main proposed solutions are based on active inductors or, as in this paper, active capacitors. The first kind involves a feedback network (typically a gyra-tor) with a transistor that emulates an inductance, removing issues typically caused by physical inductors [6][7][8][9]. Since the real inductor is removed, those filters tend to have a higher Q compared with the other topologies [10] and are suitable choices for integrated systems [11].…”