S. Lucyszyn et Id. Robertson, MONOLITHIC NARROW-BAND-FILTER USING ULTRAHIGH-Q TUNABLE ACTIVE INDUCTORS, IEEE transactions on microwave theory and techniques, 42(12), 1994, pp. 2617-2622
A tunable active inductor is presented where the novel topology enable
s both the inductance and series resistance to be varied. With a discr
ete MMIC realization of this active inductor, Q-factors in excess of 1
5 000 have been measured over a wide range of inductance values. Appli
cations for these active inductors include high-performance narrow-ban
d filters, voltage controlled oscillators, and analog phase shifters.
Analytical equations for the novel active inductor and a 3-resonator f
ilter are given. The measured performance for a monolithic 2 GHz filte
r achieves a mean insertion loss of 0.9 dB, passband ripple of +/-0.7
dB, with a 3 dB bandwidth of 70 MHz, and an excellent out-of-band reje
ction which exceeds 50 dB up to 18 GHz.